SURYAMG

IIT/JEE Mathematics Complete Foundation Hub

Comprehensive Chapter-by-Chapter Syllabus with All Models, Shortcut Tricks and Practice Problems (Classes 6 to 10)

Class 6 Foundation Modules (All Chapters & Complete Models)

Model A: LCM and HCF Relationship & Prime Factorization

Definition: HCF is the greatest common factor dividing numbers evenly, while LCM is the smallest multiple shared by numbers.

Product of two numbers = HCF(a, b) x LCM(a, b)

Shortcut Trick: For co-prime numbers, LCM is their direct product. If smaller divides larger, LCM is the larger number.

Examples & Explanations:

  • Example 1: Find HCF and LCM of 24 and 36.
    Explanation: HCF = 12. Using formula: (24 x 36) / 12 = 72 (LCM).
  • Example 2: Find LCM of 5 and 12.
    Explanation: Co-prime numbers, so LCM = 5 x 12 = 60.

Homework Problems:

  • 1. Find LCM of 14, 21, 42.
  • 2. HCF is 11, LCM is 770. One number is 275, find the other.
  • 3. Greatest 4-digit number divisible by 15, 25, 40.
  • 4. Smallest number divided by 8, 12, 16 leaving remainder 3.

Model B: Advanced Divisibility Tests

Definition: Rules to check number divisibility without full division.

Divisibility by 11: Difference of sum of odd and even placed digits is 0 or divisible by 11.

Shortcut Trick: For divisibility by 72, check divisibility by both 8 and 9 simultaneously.

Examples & Explanations:

  • Example 1: Test divisibility of 1331 by 11.
    Explanation: (1+3) - (3+1) = 0. Divisible.
  • Example 2: Test divisibility of 720 by 72.
    Explanation: Divisible by 8 (last 3 digits rule) and 9 (sum of digits 9). Hence divisible.

Homework Problems:

  • 1. Test if 918082 is divisible by 11.
  • 2. Find value of missing digit x if 543x2 is divisible by 9.
  • 3. Check divisibility of 8460 by 36.
  • 4. Find if 1001 is divisible by 7, 11, and 13.

Model A: Integers Number Line & Absolute Value

Definition: Integers include negative numbers, zero, and positive numbers. Absolute value represents distance from zero.

abs(x) = x if x >= 0 else -x

Shortcut Trick: Subtracting a negative integer is identical to adding its positive counterpart.

Examples & Explanations:

  • Example 1: Evaluate abs(-15) - abs(8).
    Explanation: 15 - 8 = 7.
  • Example 2: Simplify -25 - (-12).
    Explanation: -25 + 12 = -13.

Homework Problems:

  • 1. Evaluate abs(-45) + abs(32) - abs(-10).
  • 2. Find sum of integers between -5 and 5.
  • 3. Subtract -125 from -35.
  • 4. If temperature drops by 4 degrees every hour for 6 hours from +10 degrees, find final temperature.

Model B: Operations & Properties on Integers

Definition: Closure, commutative, associative, and distributive laws over integer operations.

a x (b + c) = (a x b) + (a x c)

Shortcut Trick: Count negative signs in multiplication: even count gives positive product, odd count gives negative product.

Examples & Explanations:

  • Example 1: Evaluate (-2) x (-3) x (-4) x (-5).
    Explanation: Four negative signs (even), result is positive 120.
  • Example 2: Compute 75 x 102 using distributive law.
    Explanation: 75 x (100 + 2) = 7500 + 150 = 7650.

Homework Problems:

  • 1. Evaluate (-15) x (-2) x (-3) x 4.
  • 2. Simplify using properties: 625 x (-35) + (-625) x 65.
  • 3. Find product of first 10 negative integers.
  • 4. Verify distributive property for a = -12, b = 5, c = -3.

Model A: Fractions Comparison & Operations

Definition: Proper, improper, and mixed fractions and their arithmetic manipulations.

a/b + c/d = (ad + bc) / bd

Shortcut Trick: Cross-multiply to compare fractions: for a/b and c/d, compare ad and bc products.

Examples & Explanations:

  • Example 1: Compare 5/8 and 7/11.
    Explanation: 5x11 = 55 and 8x7 = 56. Since 55 < 56, 5/8 < 7/11.
  • Example 2: Simplify 2/3 + 3/4 + 1/6.
    Explanation: LCM of denominators is 12. (8 + 9 + 2)/12 = 19/12.

Homework Problems:

  • 1. Arrange in ascending order: 3/5, 7/10, 11/15, 4/5.
  • 2. Evaluate: 5(1/4) - 2(3/8) + 1(1/2).
  • 3. What fraction must be added to 3/7 to get 4/5?
  • 4. Simplify: (2/3) of (4/5) / (8/15).

Model B: Decimals & Recurring Decimals

Definition: Converting decimals to fractions and handling repeating decimal expansions.

0.a (bar) = a / 9, 0.ab (bar) = ab / 99

Shortcut Trick: For mixed recurring decimals like 0.a_bar(b), use formula: (ab - a) / 90.

Examples & Explanations:

  • Example 1: Convert 0.35 (bar on 35) to fraction.
    Explanation: 35 / 99.
  • Example 2: Convert 0.26 (bar on 6) to fraction.
    Explanation: (26 - 2) / 90 = 24 / 90 = 4 / 15.

Homework Problems:

  • 1. Convert 0.54 (bar on 54) into simple fraction.
  • 2. Evaluate: 2.34 + 0.002 - 1.25.
  • 3. Convert 0.312 (bar on 12) into fraction.
  • 4. Find value of (0.2 x 0.3) / 0.05.

Model A: Ratio & Proportion Direct Problems

Definition: Comparing quantities in same units and expressing proportionality equality.

If a:b = c:d, then ad = bc

Shortcut Trick: To divide quantity Q in ratio m:n, shares are Q*m/(m+n) and Q*n/(m+n).

Examples & Explanations:

  • Example 1: Divide 630 in ratio 3:4.
    Explanation: Parts = 7. Shares = (3/7)x630=270 and (4/7)x630=360.
  • Example 2: Find fourth proportional to 3, 5, 21.
    Explanation: 3:5 = 21:x implies 3x = 105 implies x = 35.

Homework Problems:

  • 1. Two numbers are in ratio 5:8. If sum is 130, find numbers.
  • 2. Find mean proportional between 4 and 25.
  • 3. What number must be added to each term of 7:13 to make it 2:3?
  • 4. If A:B = 2:3 and B:C = 4:5, find A:B:C.

Model B: Unitary Method & Word Applications

Definition: Finding value of single unit to solve complex rate and work problems.

Men1 x Days1 = Men2 x Days2 (for constant work)

Shortcut Trick: Inverse proportion: if more workers decrease days, product of workers and days remains constant.

Examples & Explanations:

  • Example 1: If 15 men complete work in 20 days, how many days for 25 men?
    Explanation: 15 x 20 = 25 x d implies d = 300/25 = 12 days.
  • Example 2: Cost of 8 pens is 96 units. Cost of 15 pens?
    Explanation: Unit cost = 96/8 = 12. 15 x 12 = 180 units.

Homework Problems:

  • 1. If 12 cows eat as much as 18 goats, how many cows eat as much as 27 goats?
  • 2. Train travels 300km in 4 hours. How long to travel 450km at same speed?
  • 3. 20 men can dig a pond in 15 days. How many days for 12 men?
  • 4. Cost of 5kg rice is 250 units. Find cost of 12kg rice.

Model A: Lines, Angles & Pairs

Definition: Complementary angles sum to 90 degrees; supplementary angles sum to 180 degrees.

Linear pair angles sum = 180 degrees

Shortcut Trick: Vertically opposite angles formed by two intersecting lines are always equal.

Examples & Explanations:

  • Example 1: Find complement of 35 degrees.
    Explanation: 90 - 35 = 55 degrees.
  • Example 2: Two supplementary angles are in ratio 2:3. Find them.
    Explanation: 2x + 3x = 180 implies x = 36. Angles: 72 and 108 degrees.

Homework Problems:

  • 1. Find supplement of 125 degrees.
  • 2. An angle is equal to its complement. Find measure.
  • 3. Two complementary angles are in ratio 4:5. Find them.
  • 4. If two intersecting lines form angle 65 degrees, find remaining three angles.

Model B: Polygons & Diagonals

Definition: Convex and concave polygons, interior/exterior angle sums, and diagonals count.

Diagonals = n(n-3)/2, Interior Sum = (n-2) x 180 degrees

Shortcut Trick: Sum of exterior angles of any convex polygon is always identically 360 degrees.

Examples & Explanations:

  • Example 1: Find diagonals in a decagon (10 sides).
    Explanation: 10(7)/2 = 35 diagonals.
  • Example 2: Find each interior angle of regular hexagon.
    Explanation: (4 x 180) / 6 = 120 degrees.

Homework Problems:

  • 1. Find number of sides of polygon with 20 diagonals.
  • 2. Sum of interior angles of 12-sided polygon.
  • 3. Each exterior angle of regular polygon is 40 degrees. Find sides.
  • 4. Interior angle of regular polygon is 5 times its exterior angle. Find sides.

Model A: Perimeter & Area of Rectilinear Figures

Definition: Perimeter is outer boundary length; area is 2D surface coverage of rectangles and squares.

Rectangle Area = l x b, Perimeter = 2(l + b)

Shortcut Trick: If side of square increases by x percent, area increases by (2x + x^2/100) percent.

Examples & Explanations:

  • Example 1: Find perimeter of rectangular park 40m long and 25m wide.
    Explanation: 2(40 + 25) = 130m.
  • Example 2: Side of square increases by 10%. Area increase?
    Explanation: 2(10) + 1 = 21%.

Homework Problems:

  • 1. Cost of fencing rectangular field 60m by 40m at 15 units/m.
  • 2. Find area of four walls of room 12m long, 8m wide, 4m high.
  • 3. Side of square is 15cm. Find perimeter and area.
  • 4. Area of rectangle is 300 cm^2 and length is 20cm. Find breadth and perimeter.

Model B: Pathways & Mixed Mensuration Problems

Definition: Calculating areas of internal and external paths running across rectangular fields.

Path inside of width w: Area = 2w(L + B - 2w)

Shortcut Trick: Cross paths running parallel to length and breadth: Area = w(L + B - w).

Examples & Explanations:

  • Example 1: Field 40m by 30m with 2m wide path running inside. Find path area.
    Explanation: 2(2)(40 + 30 - 4) = 4(66) = 264 m^2.
  • Example 2: Cross paths 3m wide through center of 50m x 30m field.
    Explanation: 3(50 + 30 - 3) = 3(77) = 231 m^2.

Homework Problems:

  • 1. Path 2.5m wide runs outside a garden 45m long and 30m wide. Find path area.
  • 2. Garden 60m x 40m has two cross roads 2m wide in center. Find remaining garden area.
  • 3. Floor of room 10m x 8m is paved with square tiles of side 20cm. Find tiles count.
  • 4. Find cost of gravelling path 3m wide around circular garden of radius 14m at 10 units/m^2.

Model A: Data Collection, Tally Marks & Pictographs

Definition: Recording raw data using tally counts and representing frequencies visually via picture symbols.

Frequency = Count of occurrences of a specific observation

Shortcut Trick: Tally marks are grouped in bunches of 5 (four vertical lines with a diagonal strike through).

Examples & Explanations:

  • Example 1: Represent frequency 7 using tallies.
    Explanation: IIII followed by II.
  • Example 2: Pictograph symbol represents 10 cars. How many symbols for 45 cars?
    Explanation: 4 full symbols and 1 half symbol.

Homework Problems:

  • 1. Draw tally marks for frequencies: 12, 17, 8.
  • 2. If symbol represents 25 books, how many symbols for 175 books?
  • 3. Prepare frequency distribution table for scores: 5, 2, 3, 5, 4, 2, 5, 3, 4, 2, 5.
  • 4. State difference between pictograph and bar graph.

Model B: Mean, Median & Bar Graphs

Definition: Arithmetic mean measures average, median measures middle value, and bar graphs display categorical data.

Mean = Sum of observations / Total count

Shortcut Trick: To find median of n observations, arrange in ascending order and pick middle term (n+1)/2 if odd, or average of two middle terms if even.

Examples & Explanations:

  • Example 1: Find mean of first 5 prime numbers (2, 3, 5, 7, 11).
    Explanation: Sum = 28. Mean = 28 / 5 = 5.6.
  • Example 2: Find median of 12, 7, 15, 9, 20.
    Explanation: Sorted: 7, 9, 12, 15, 20. Median = 12.

Homework Problems:

  • 1. Find mean and median of scores: 85, 90, 75, 80, 95, 88.
  • 2. Mean of 5 numbers is 18. If one number is excluded, mean becomes 16. Find excluded number.
  • 3. Find mode of data: 3, 5, 7, 3, 9, 3, 5, 2, 3.
  • 4. Interpret bar graph representing production of cars from 2020 to 2024 to find maximum growth year.

Class 7 Foundation Modules (All Chapters & Complete Models)

Model A: Rational Numbers Properties & Operations

Definition: Numbers expressed as p/q where q is not equal to 0 and integers p, q. Properties include closure, commutativity, and associativity.

Multiplicative inverse of a/b is b/a

Shortcut Trick: To find midway rational number between a and b, use arithmetic mean (a + b) / 2.

Examples & Explanations:

  • Example 1: Find rational number midway between 1/3 and 1/2.
    Explanation: (1/3 + 1/2)/2 = (5/6)/2 = 5/12.
  • Example 2: Evaluate (-3/5) x (15/9).
    Explanation: -45 / 45 = -1.

Homework Problems:

  • 1. Find 3 rational numbers between -2 and 3.
  • 2. Verify associative property for addition of -2/3, 3/5, and -1/6.
  • 3. Simplify: (-7/12) / (28/-36).
  • 4. Find multiplicative inverse of (-3/5) x (-10/9).

Model B: Density & Representation on Number Line

Definition: Infinitely many rational numbers exist between any two distinct rational numbers.

Common difference to insert n rational numbers between a and b: d = (b - a)/(n + 1)

Shortcut Trick: To insert 3 numbers between a and b, use sequence: a + d, a + 2d, a + 3d.

Examples & Explanations:

  • Example 1: Insert 2 rational numbers between 1 and 2.
    Explanation: d = (2 - 1)/(2 + 1) = 1/3. Numbers: 4/3 and 5/3.
  • Example 2: Represent -5/4 on number line.
    Explanation: Divide segment between -1 and -2 into 4 equal parts, locate 5th division left of zero.

Homework Problems:

  • 1. Find 5 rational numbers between 3/5 and 4/5.
  • 2. Represent -7/3 on number line.
  • 3. Insert 4 rational numbers between -1/2 and 1/2.
  • 4. Check if -3/5 is less than -2/3.

Model A: Complex Fractions & Series Cancellation

Definition: Advanced fractional operations involving multi-story fractions and telescopic series cancellations.

1 / (n(n+1)) = 1/n - 1/(n+1)

Shortcut Trick: Telescopic sum: 1/(1x2) + 1/(2x3) + ... + 1/(n(n+1)) = n/(n+1).

Examples & Explanations:

  • Example 1: Evaluate 1/(1x2) + 1/(2x3) + 1/(3x4).
    Explanation: Using formula for n=3: 3 / (3+1) = 3/4.
  • Example 2: Simplify 1 / (1 + 1 / (1 + 1/2)).
    Explanation: 1 + 1/2 = 3/2. 1/(3/2) = 2/3. 1 + 2/3 = 5/3. 1/(5/3) = 3/5.

Homework Problems:

  • 1. Evaluate: 1/(1x2) + 1/(2x3) + ... + 1/(9x10).
  • 2. Simplify: (3/4) / (9/16) of (8/15).
  • 3. Find value of 2 / (1 + 1 / (1 - 1/3)).
  • 4. Evaluate: (1 - 1/2)(1 - 1/3)(1 - 1/4)...(1 - 1/n).

Model B: Decimal Operations & BODMAS Simplification

Definition: Strict order of operations (Brackets, Of, Division, Multiplication, Addition, Subtraction) with decimals.

BODMAS Priority: B -> O -> D -> M -> A -> S

Shortcut Trick: Align decimal points carefully during addition/subtraction; shift decimal right equal to total zeroes in multiplier.

Examples & Explanations:

  • Example 1: Evaluate 2.5 x 1.2 + 3.6 / 0.4.
    Explanation: 3.0 + 9.0 = 12.0.
  • Example 2: Simplify 15.5 - {4.2 + (3.1 - 1.1)}.
    Explanation: Inner bracket = 2.0. Curly brace = 6.2. Result = 15.5 - 6.2 = 9.3.

Homework Problems:

  • 1. Simplify: 25.4 - [12.2 - {5.1 + (3.4 - 1.2)}].
  • 2. Evaluate: 0.04 x 0.003 x 400.
  • 3. Simplify using BODMAS: 18 - [5 - {6 - (5 - 4 - 3)}].
  • 4. Find value of (2.3 x 2.3 - 1.3 x 1.3) / (2.3 - 1.3) using algebraic expansion.

Model A: Laws of Exponents & Simplification

Definition: Rules governing exponents with integer bases and powers.

a^m x a^n = a^(m+n), a^m / a^n = a^(m-n), (a^m)^n = a^(m x n)

Shortcut Trick: Any non-zero base raised to power zero is identically 1 (a^0 = 1). Negative exponent inverts the base.

Examples & Explanations:

  • Example 1: Simplify (2^3)^2 x 2^4 / 2^5.
    Explanation: 2^6 x 2^4 / 2^5 = 2^(6+4-5) = 2^5 = 32.
  • Example 2: Evaluate (3/4)^(-2) x (4/3)^(-3).
    Explanation: (4/3)^2 x (3/4)^3 = (16/9) x (27/64) = 3/4.

Homework Problems:

  • 1. Find x if (3/5)^3 x (3/5)^(-6) = (3/5)^(2x-1).
  • 2. Evaluate: ((6^(-1) - 8^(-1))^(-1) + (3^(-1) - 4^(-1))^(-1)).
  • 3. Simplify: (2^0 + 3^0 + 4^0) x 5^2.
  • 4. Find value of m if (5/3)^(-2) x (5/3)^(-14) = (5/3)^(8m).

Model B: Comparing Large Powers & Standard Form

Definition: Expressing very large or small numbers in standard scientific notation k x 10^n (1 <= k < 10).

Standard form: a.bc x 10^n

Shortcut Trick: To compare numbers with large powers like 2^60 and 3^40, find HCF of exponents (20), express as (2^3)^20 and (3^2)^20.

Examples & Explanations:

  • Example 1: Express 0.0000456 in standard form.
    Explanation: 4.56 x 10^(-5).
  • Example 2: Which is larger: 2^300 or 3^200?
    Explanation: (2^3)^100 = 8^100 vs (3^2)^100 = 9^100. 3^200 is larger.

Homework Problems:

  • 1. Express 45,600,000 in standard scientific notation.
  • 2. Which is larger: 2^50 or 3^40?
  • 3. Write 0.0000000342 in standard form.
  • 4. Compare 5^30 and 3^50 using exponent HCF reduction.

Model A: Algebraic Identities & Expansion

Definition: Fundamental algebraic identities for squaring binomials and difference of squares.

(a + b)^2 = a^2 + 2ab + b^2, (a - b)^2 = a^2 - 2ab + b^2, a^2 - b^2 = (a-b)(a+b)

Shortcut Trick: To evaluate products like 103 x 97 rapidly, rewrite as (100 + 3)(100 - 3) = 100^2 - 3^2 = 9991.

Examples & Explanations:

  • Example 1: Expand (3x + 4y)^2.
    Explanation: (3x)^2 + 2(3x)(4y) + (4y)^2 = 9x^2 + 24xy + 16y^2.
  • Example 2: Evaluate 102 x 98.
    Explanation: (100 + 2)(100 - 2) = 10000 - 4 = 9996.

Homework Problems:

  • 1. Expand: (2x - 5y)^2.
  • 2. Evaluate using identity: 105 x 95.
  • 3. Simplify: (a + b)^2 - (a - b)^2.
  • 4. Expand: (2x - 3y + 4z)^2.

Model B: Reciprocal Algebraic Shortcuts (x + 1/x)

Definition: Advanced manipulation of reciprocal variable expressions to find higher powers.

If x + 1/x = k, then x^2 + 1/x^2 = k^2 - 2 and x^3 + 1/x^3 = k^3 - 3k

Shortcut Trick: For minus reciprocals: if x - 1/x = k, then x^2 + 1/x^2 = k^2 + 2 and x^3 - 1/x^3 = k^3 + 3k.

Examples & Explanations:

  • Example 1: If x + 1/x = 4, find x^2 + 1/x^2.
    Explanation: 4^2 - 2 = 14.
  • Example 2: If x - 1/x = 3, find x^3 - 1/x^3.
    Explanation: 3^3 + 3(3) = 27 + 9 = 36.

Homework Problems:

  • 1. If x + 1/x = 5, find x^3 + 1/x^3.
  • 2. If x - 1/x = 4, find x^2 + 1/x^2.
  • 3. If x + 1/x = 3, find x^4 + 1/x^4.
  • 4. If a + b + c = 12 and ab + bc + ca = 47, find a^2 + b^2 + c^2.

Model A: Parallel Lines & Transversal Angles

Definition: Corresponding angles, alternate interior angles, and consecutive interior angles formed by transversal cutting parallels.

Consecutive interior angles sum = 180 degrees

Shortcut Trick: If two lines are parallel to the same line, they are parallel to each other.

Examples & Explanations:

  • Example 1: Parallel lines cut by transversal; one interior angle is 70 degrees. Find alternate interior angle.
    Explanation: 70 degrees (alternate angles are equal).
  • Example 2: Co-interior angles are in ratio 2:3. Find them.
    Explanation: 2x + 3x = 180 implies x = 36. Angles: 72 and 108 degrees.

Homework Problems:

  • 1. Two parallel lines are intersected by transversal. One angle is 65 degrees. Find all 8 angles.
  • 2. Co-interior angles are (3x - 10) and (2x + 20). Find x and angles.
  • 3. Prove that lines perpendicular to same line are parallel to each other.
  • 4. Find angle x if two parallel lines are cut by transversal forming exterior angles 3x + 10 and 5x - 30.

Model B: Triangles Properties & Inequality Theorem

Definition: Angle sum property, exterior angle theorem, and triangle side length bounds.

Exterior angle = Sum of two interior opposite angles

Shortcut Trick: Triangle inequality: sum of any two sides is greater than the third side, and difference is less than third side.

Examples & Explanations:

  • Example 1: Exterior angle is 110 degrees, opposite interior angle is 40 degrees. Find other.
    Explanation: 110 - 40 = 70 degrees.
  • Example 2: Triangle sides are 7cm and 11cm. Bounds for third side?
    Explanation: 11 - 7 < c < 11 + 7 implies 4 < c < 18.

Homework Problems:

  • 1. Can a triangle have sides 4cm, 5cm, 10cm? Justify.
  • 2. In right triangle, acute angles are in ratio 2:3. Find angles.
  • 3. Angles of triangle are in ratio 2:3:4. Find largest angle.
  • 4. In triangle ABC, angle A = 50 degrees and external bisectors of B and C meet at O. Find angle BOC.

Model A: Percentage, Successive Discounts & Profit/Loss

Definition: Percentage calculations, markup, discount on marked price, and successive percentage changes.

Equivalent successive discount for a% and b% = a + b - (ab)/100

Shortcut Trick: If SP is identical for two items, one sold at x% profit and other at x% loss, overall transaction always yields net loss of (x^2)/100 percent.

Examples & Explanations:

  • Example 1: Find single equivalent discount for 20% and 10%.
    Explanation: 20 + 10 - 2 = 28%.
  • Example 2: Two items sold for 99 units each, 10% profit on one and 10% loss on other. Net loss?
    Explanation: (10^2)/100 = 1% loss.

Homework Problems:

  • 1. Dealer marks goods 30% above CP and gives 10% discount. Find profit percent.
  • 2. Single equivalent discount for successive discounts of 10%, 20%, 25%.
  • 3. By selling 33 meters of cloth, person gains SP of 11 meters. Find gain percent.
  • 4. Price of sugar increases by 25%. By what percent must family reduce consumption?

Model B: Simple Interest & Word Problems

Definition: Calculating interest earned over principal amount across time periods at fixed annual percentage rate.

Simple Interest SI = (P x R x T) / 100, Amount A = P + SI

Shortcut Trick: If a sum becomes n times in T years at simple interest, rate is given by R = 100(n - 1) / T.

Examples & Explanations:

  • Example 1: Find SI on 15,000 units at 12% per annum for 3 years.
    Explanation: (15000 x 12 x 3) / 100 = 5400 units.
  • Example 2: Sum becomes 3 times in 10 years at SI. Find rate.
    Explanation: 100(3 - 1) / 10 = 200 / 10 = 20% per annum.

Homework Problems:

  • 1. In what time will 5,000 units amount to 7,000 units at 8% per annum SI?
  • 2. Sum becomes double in 8 years at SI. Find time to become 4 times.
  • 3. A sum was put at SI at certain rate for 3 years. Had it been put at 2% higher rate, it would have fetched 360 units more. Find sum.
  • 4. Find principal that yields 400 units interest at 5% per annum in 4 years.

Model A: Area of Circles, Parallelograms & Trapeziums

Definition: Mensuration formulas for 2D geometrical shapes including circles, sectors, rhombuses, and trapeziums.

Trapezium Area = 0.5 x (sum of parallel sides) x height, Circle Area = pi x r^2

Shortcut Trick: Area of circular path (ring) with outer radius R and inner radius r is pi x (R + r)(R - r).

Examples & Explanations:

  • Example 1: Find area of circle with radius 14cm.
    Explanation: (22/7) x 14 x 14 = 616 cm^2.
  • Example 2: Trapezium parallel sides are 12cm and 8cm, height 5cm. Area?
    Explanation: 0.5 x (12 + 8) x 5 = 50 cm^2.

Homework Problems:

  • 1. Find circumference of circle whose area is 616 cm^2.
  • 2. Find area of rhombus whose diagonals are 16cm and 12cm.
  • 3. Area of trapezium is 480 cm^2 and height is 15cm. One parallel side is 20cm, find other.
  • 4. Find area of circular path of width 7cm surrounding circular garden of radius 21cm.

Model B: Cuboids, Cubes Volume & Surface Area

Definition: Total surface area, lateral surface area, and volume of 3D boxes and cubes.

Cube Volume = a^3, TSA = 6a^2, Cuboid Volume = l x b x h

Shortcut Trick: If edge of cube is increased by x%, volume increases by approximately 3x% for small increments.

Examples & Explanations:

  • Example 1: Find volume of cube with edge 8cm.
    Explanation: 8^3 = 512 cm^3.
  • Example 2: Cuboid dimensions 10cm x 8cm x 6cm. Find TSA.
    Explanation: 2(80 + 48 + 60) = 2(188) = 376 cm^2.

Homework Problems:

  • 1. Find total surface area of cube of volume 343 cm^3.
  • 2. Cuboid water tank is 6m long, 5m wide, 4.5m deep. How many liters of water can it hold? (1 m^3 = 1000 liters).
  • 3. Three cubes of metal edges 3cm, 4cm, and 5cm are melted to form single cube. Find edge of new cube.
  • 4. Find lateral surface area of cuboid of dimensions 12cm x 8cm x 5cm.

Class 8 Foundation Modules (All Chapters & Complete Models)

Model A: Rational Numbers Properties & Distributivity

Definition: Closure, commutative, associative, and distributive laws over rational numbers.

Distributive Property: a(b + c) = ab + ac

Shortcut Trick: Rearrange terms using commutative and associative properties to group fractions with common denominators before calculation.

Examples & Explanations:

  • Example 1: Multiplicative inverse of -13/19.
    Explanation: -19/13.
  • Example 2: Evaluate 2/5 x (-3/7) - 1/14 - 3/7 x 3/5 using rearrangement.
    Explanation: Group terms with 3/7: 3/5(-2/7 - 3/7) - 1/14 = 3/5(-5/7) - 1/14 = -3/7 - 1/14 = -7/14 = -1/2.

Homework Problems:

  • 1. Using appropriate properties find: 2/5 x (-3/7) - 1/6 x 3/2 + 1/14 x 2/5.
  • 2. Verify multiplicative identity and additive identity for -7/11.
  • 3. Name property used in: -2/7 x 1 = 1 x -2/7 = -2/7.
  • 4. Verify distributive property for a = -3/4, b = 2/3, c = -5/6.

Model B: Density & Inserting Rational Numbers

Definition: Finding multiple rational numbers between any two numbers.

Common difference d = (b - a) / (n + 1)

Shortcut Trick: Make denominators equal using LCM, then scale numerators by multiplying top and bottom by (n + 1).

Examples & Explanations:

  • Example 1: Find 3 rational numbers between 1/4 and 1/2.
    Explanation: Denominators to 8: 2/8 and 4/8. Scale by 4: 8/32 and 16/32. Numbers: 9/32, 10/32, 11/32.
  • Example 2: Insert 5 rational numbers between -3 and 3.
    Explanation: d = (3 - (-3))/6 = 6/6 = 1. Numbers: -2, -1, 0, 1, 2.

Homework Problems:

  • 1. Find 10 rational numbers between -3/5 and 3/4.
  • 2. Insert 5 rational numbers between 2/3 and 4/5.
  • 3. Find 6 rational numbers between -2 and -1.
  • 4. Insert 4 rational numbers between -1/3 and 1/2.

Model A: Linear Equations Cross-Multiplication Method

Definition: Solving equations reducible to linear form with fractional expressions.

If (ax+b)/(cx+d) = p/q, then q(ax+b) = p(cx+d)

Shortcut Trick: Cross-multiply immediately when single fractions equal single fractions on both sides.

Examples & Explanations:

  • Example 1: Solve (x + 1)/(2x + 3) = 3/8.
    Explanation: 8(x+1) = 3(2x+3) implies 8x+8 = 6x+9 implies 2x = 1 implies x = 1/2.
  • Example 2: Solve (3x + 1) / 5 = (2x - 3) / 3.
    Explanation: 3(3x + 1) = 5(2x - 3) implies 9x + 3 = 10x - 15 implies x = 18.

Homework Problems:

  • 1. Solve: (6x + 1)/3 + 1 = (x - 3)/6.
  • 2. Solve for x: (x - 5)/2 - (x - 3)/5 = 1/2.
  • 3. Solve: (2x - 3)/(3x + 2) = -2/3.
  • 4. Solve: (7x + 2) / (2x + 5) = 3/8.

Model B: Word Problems (Age, Stream & Numbers)

Definition: Translating verbal real-world statements into mathematical linear equations.

Speed downstream = u + v, Speed upstream = u - v

Shortcut Trick: For consecutive number problems, let numbers be x, x+1, x+2 or x, x+2, x+4 for evens/odds.

Examples & Explanations:

  • Example 1: Sum of 3 consecutive multiples of 8 is 888. Find them.
    Explanation: 3x + 24 = 888 implies x = 288. Numbers: 288, 296, 304.
  • Example 2: Baichung's father is 29 years older than Baichung and 26 years younger than grandfather. Sum of ages is 135.
    Explanation: Let Baichung be x. Father x+29, grandfather x+55. 3x + 84 = 135 implies 3x = 51 implies x = 17. Ages: 17, 46, 72.

Homework Problems:

  • 1. Sum of two numbers is 95. If one exceeds other by 15, find numbers.
  • 2. Baichung's grandfather is 26 years older than father and 29 years older than Baichung. Sum of ages 135. Find father's age.
  • 3. Boat goes 30km downstream in 2 hours and 15km upstream in 3 hours. Find speed of stream.
  • 4. Two digits number has sum of digits 9. When digits are interchanged, new number exceeds original by 27. Find number.

Model A: Square Roots Estimation & Non-Perfect Squares

Definition: Finding exact and approximate square roots using long division and binomial expansion approximation.

sqrt(a^2 + b) approx a + b / (2a)

Shortcut Trick: Denesting formula: sqrt((x + y) + 2*sqrt(xy)) = sqrt(x) + sqrt(y).

Examples & Explanations:

  • Example 1: Find approximate sqrt(50).
    Explanation: sqrt(49 + 1) approx 7 + 1/14 = 7.071.
  • Example 2: Evaluate sqrt(7 + 4*sqrt(3)).
    Explanation: sqrt(4 + 3 + 2(2)sqrt(3)) = 2 + sqrt(3).

Homework Problems:

  • 1. Find square root of 729 by prime factorization and long division.
  • 2. Evaluate sqrt(0.9) up to three decimal places.
  • 3. Evaluate: sqrt(248 + sqrt(52 + sqrt(144))).
  • 4. Find smallest number by which 2880 must be multiplied to make it a perfect square.

Model B: Cubes, Cube Roots & Prime Factor Grouping

Definition: Cubes of numbers and extracting cube roots by grouping prime factors in triplets.

Prime factor grouping: Cube root groups identical factors in triplets (a^3)^(1/3) = a

Shortcut Trick: Unit digit of cube root follows specific repeating cycles.

Examples & Explanations:

  • Example 1: Find cube root of 17576.
    Explanation: Factors give 2^3 x 13^3, so cube root is 2 x 13 = 26.
  • Example 2: Smallest number to multiply 135 to make it a perfect cube?
    Explanation: 135 = 3^3 x 5. Need two more 5s, so multiply by 25.

Homework Problems:

  • 1. Find cube root of 10648 through prime factor grouping.
  • 2. Smallest number by which 392 must be divided to make it a perfect cube.
  • 3. Evaluate cube root of 0.000216.
  • 4. Find volume of cube whose surface area is 600 cm^2, then find edge cube root.

Model A: Parallelograms & Special Quadrilaterals Properties

Definition: Properties of parallelograms, rhombuses, rectangles, squares, and trapeziums regarding sides, angles, and diagonals.

Diagonals of a rhombus bisect each other at right angles (90 degrees).

Shortcut Trick: Adjacent angles of any parallelogram are supplementary (sum to 180 degrees).

Examples & Explanations:

  • Example 1: Adjacent angles of parallelogram are in ratio 3:2. Find angles.
    Explanation: 3x + 2x = 180 implies x = 36. Angles: 108, 72, 108, 72 degrees.
  • Example 2: Diagonals of rhombus are 16cm and 12cm. Find side.
    Explanation: Side = sqrt(8^2 + 6^2) = 10cm.

Homework Problems:

  • 1. In parallelogram ABCD, angle A = (3x - 10) and angle C = (2x + 30). Find all angles.
  • 2. Diagonals of rhombus are 24cm and 10cm. Find perimeter.
  • 3. Perimeter of parallelogram is 150cm and one side is greater than other by 25cm. Find sides.
  • 4. Prove that angle bisectors of a parallelogram form a rectangle.

Model B: Polygon Angle Sums & Exterior Angle Theorem

Definition: Relationship between interior and exterior angles of convex polygons.

Sum of all exterior angles of any convex polygon = 360 degrees

Shortcut Trick: Number of sides n = 360 / (Exterior Angle) for regular polygons.

Examples & Explanations:

  • Example 1: Find number of sides of regular polygon if each exterior angle is 40 degrees.
    Explanation: 360 / 40 = 9 sides.
  • Example 2: Each interior angle of regular polygon is 165 degrees. Find sides.
    Explanation: Exterior angle = 180 - 165 = 15 degrees. Sides = 360 / 15 = 24.

Homework Problems:

  • 1. Find number of sides of regular polygon whose each exterior angle is 30 degrees.
  • 2. Is it possible to have regular polygon with measure of each exterior angle as 22 degrees? Why?
  • 3. Find measure of each interior angle of regular pentagon and regular octagon.
  • 4. The interior and exterior angles are in ratio 5:1. Find number of sides of polygon.

Model A: Algebraic Identities & Factorization by Grouping

Definition: Factorization using common terms, regrouping, and standard algebraic identities.

a^3 + b^3 = (a+b)(a^2 - ab + b^2), a^3 - b^3 = (a-b)(a^2 + ab + b^2)

Shortcut Trick: Difference of two squares: a^4 - b^4 = (a^2 - b^2)(a^2 + b^2) = (a-b)(a+b)(a^2+b^2).

Examples & Explanations:

  • Example 1: Factorize x^4 - 81.
    Explanation: (x^2 - 9)(x^2 + 9) = (x - 3)(x + 3)(x^2 + 9).
  • Example 2: Factorize 8x^3 + 27y^3.
    Explanation: (2x + 3y)(4x^2 - 6xy + 9y^2).

Homework Problems:

  • 1. Factorize completely: x^4 - 625.
  • 2. Factorize: x^2 - y^2 - 6y - 9.
  • 3. Factorize: 64a^3 - 125b^3.
  • 4. Factorize: ax + ay + bx + by by grouping.

Model B: Splitting Middle Term for Quadratics (ax^2 + bx + c)

Definition: Factoring quadratic expressions by splitting middle term into two parts whose product is ac and sum is b.

For ax^2 + bx + c, find p, q such that p*q = ac and p+q = b

Shortcut Trick: Signs of factors: if middle term is positive and constant is positive, both factors are positive.

Examples & Explanations:

  • Example 1: Factorize x^2 + 7x + 12.
    Explanation: Numbers 4 and 3. (x + 4)(x + 3).
  • Example 2: Factorize 6x^2 + 5x - 6.
    Explanation: Product = -36, sum = 5 (factors 9 and -4). Result = (3x - 2)(2x + 3).

Homework Problems:

  • 1. Factorize: x^2 - 10x + 21.
  • 2. Factorize: 2x^2 + 7x + 3.
  • 3. Factorize: 12x^2 - 7x + 1.
  • 4. Factorize: x^2 - 4x - 5 using middle term splitting.

Model A: Compound Interest Formulas & Half-Yearly Compounding

Definition: Calculating compound interest, population growth, and depreciation models.

Amount A = P(1 + r/100)^n, CI = A - P

Shortcut Trick: For half-yearly compounding, double the time periods (2n) and halve the annual rate (r/2).

Examples & Explanations:

  • Example 1: Find CI on 10,000 units at 10% per annum for 2 years.
    Explanation: A = 10000(1.1)^2 = 12100. CI = 2100.
  • Example 2: CI vs SI difference for 2 years: Difference = P(r/100)^2.
    Explanation: For P=8000, r=5%, Diff = 8000(5/100)^2 = 20 units.

Homework Problems:

  • 1. Find compound interest on 10,000 units for 1.5 years at 10% per annum compounded half-yearly.
  • 2. Population of city increases by 5% annually to 92610. Find population 3 years ago.
  • 3. Difference between CI and SI on 15,000 units at 8% per annum for 2 years.
  • 4. Scooter depreciates in value by 20% every year. If current value is 40,000 units, find value after 2 years.

Model B: Direct and Inverse Proportion Word Problems

Definition: Direct variation (x/y = k) and inverse variation (x x y = k).

Direct: x1/y1 = x2/y2, Inverse: x1*y1 = x2*y2

Shortcut Trick: In inverse proportion (men and days), increase in workers causes proportional decrease in completion time.

Examples & Explanations:

  • Example 1: If 15 men complete work in 20 days, how many days for 25 men?
    Explanation: 15 x 20 = 25 x d implies d = 12 days.
  • Example 2: 6 pipes fill tank in 70 minutes. How long for 7 pipes?
    Explanation: 6 x 70 = 7 x t implies t = 60 minutes.

Homework Problems:

  • 1. If 14kg of sugar costs 420 units, how much sugar can be bought for 900 units?
  • 2. Hostel has food provisions for 60 students for 20 days. If 20 students leave, how long will food last?
  • 3. A train running at 75 km/h covers distance in 4 hours. What speed is required to cover it in 3 hours?
  • 4. If 8 workers build wall in 6 days, how many workers needed to build it in 4 days?

Model A: Cylinder & Cone Surface Area & Volume

Definition: Curved surface area, total surface area, and volume of right circular cylinders and cones.

Cylinder CSA = 2 x pi x r x h, Volume = pi x r^2 x h, Cone Volume = (1/3) x pi x r^2 x h

Shortcut Trick: Slant height of cone l = sqrt(r^2 + h^2). Cone TSA = pi x r(r + l).

Examples & Explanations:

  • Example 1: Volume of cylinder with radius 7cm and height 10cm.
    Explanation: (22/7) x 7 x 7 x 10 = 1540 cm^3.
  • Example 2: Find slant height of cone with radius 6cm and height 8cm.
    Explanation: l = sqrt(36 + 64) = 10cm.

Homework Problems:

  • 1. Find height of cylinder whose volume is 1.54 m^3 and base diameter is 140cm.
  • 2. Find total surface area of right circular cone with radius 7cm and slant height 25cm.
  • 3. Find cost of painting inner curved surface of cylindrical vessel 10m deep at 20 units/m^2 if radius is 1.4m.
  • 4. Volume of right circular cone is 1232 cm^3 and height is 24cm. Find radius.

Model B: Recasting Solids & Sphere Mensuration

Definition: Melting and recasting solid shapes where total volume remains invariant (V1 = V2).

Sphere Volume = (4/3) x pi x r^3, Surface Area = 4 x pi x r^2

Shortcut Trick: When melting sphere into cylinder, equate (4/3) x pi x R^3 = pi x r^2 x h directly.

Examples & Explanations:

  • Example 1: Metallic sphere of radius 4.2cm is melted and recast into cylinder of radius 6cm. Find height.
    Explanation: (4/3) x pi x (4.2)^3 = pi x (6^2) x h. Solving gives h = 2.74cm.
  • Example 2: Surface area of sphere of radius 7cm.
    Explanation: 4 x (22/7) x 7 x 7 = 616 cm^2.

Homework Problems:

  • 1. Find volume and surface area of sphere of radius 10.5cm.
  • 2. Metallic sphere of radius 4.2cm is melted and recast into cylinder of radius 6cm. Find height.
  • 3. Solid iron cylinder of radius 8cm and height 2cm is melted and recast into spherical balls of radius 1cm. Find count.
  • 4. Hemisphere bowl of internal radius 9cm is filled with liquid. This liquid is poured into cylindrical bottles of radius 3cm and height 4cm. Find bottles count.

Class 9 Foundation Modules (All Chapters & Complete Models)

Model A: Real Numbers & Surds Rationalization

Definition: Surds are irrational roots of rational numbers. Rationalization removes roots from denominators using conjugates.

1 / (sqrt(a) + sqrt(b)) = (sqrt(a) - sqrt(b)) / (a - b)

Shortcut Trick: Nested surd expansion: sqrt(a + sqrt(b)) = sqrt((a + sqrt(a^2-b))/2) + sqrt((a - sqrt(a^2-b))/2).

Examples & Explanations:

  • Example 1: Rationalize 2 / (sqrt(7) + sqrt(5)).
    Explanation: 2(sqrt(7) - sqrt(5)) / 2 = sqrt(7) - sqrt(5).
  • Example 2: Simplify sqrt(5 + 2*sqrt(6)).
    Explanation: Factors of 6 adding to 5 are 3 and 2. Result: sqrt(3) + sqrt(2).

Homework Problems:

  • 1. If x = 2 + sqrt(3), find x^2 + 1/x^2.
  • 2. Simplify: 4 / (3*sqrt(3) - 2*sqrt(2)) + 3 / (3*sqrt(3) + 2*sqrt(2)).
  • 3. Prove that sqrt(5) is irrational using contradiction.
  • 4. Find value of ((x^a)/(x^b))^(a+b) x ((x^b)/(x^c))^(b+c) x ((x^c)/(x^a))^(c+a).

Model B: Exponent Laws & Radical Equations

Definition: Laws of indices with rational exponents and solving equations with variables in exponents.

a^(m/n) = n-th root of (a^m)

Shortcut Trick: Equating bases: if a^x = a^y, then x = y (for a not equal to 0, 1, -1).

Examples & Explanations:

  • Example 1: Evaluate (64)^(1/3) x (125)^(2/3).
    Explanation: 4 x 25 = 100.
  • Example 2: Solve 2^(x+1) = 32.
    Explanation: 32 = 2^5, so x + 1 = 5 implies x = 4.

Homework Problems:

  • 1. Simplify: (243)^(3/5) x (32)^(-2/5).
  • 2. Solve for x: 3^(2x - 1) = 27.
  • 3. Simplify: (root(3, 8))^(-2) x (root(2, 16))^3.
  • 4. Prove that (x^(a-b))^(a+b) x (x^(b-c))^(b+c) x (x^(c-a))^(c+a) = 1.

Model A: Remainder & Factor Theorems

Definition: Remainder theorem states remainder when p(x) is divided by x - a is p(a). Factor theorem states x - a is factor if p(a) = 0.

If (x - a) is factor of p(x), then p(a) = 0

Shortcut Trick: For divisor ax - b, remainder is evaluated directly at p(b/a).

Examples & Explanations:

  • Example 1: Find remainder when x^3 - 3x^2 + 4x - 1 is divided by x - 2.
    Explanation: p(2) = 8 - 12 + 8 - 1 = 3.
  • Example 2: Check if x + 2 is factor of x^3 + 3x^2 + 5x + 6.
    Explanation: p(-2) = -8 + 12 - 10 + 6 = 0. Yes, it is a factor.

Homework Problems:

  • 1. Find remainder when 3x^4 - 4x^3 - 3x - 1 is divided by x - 1.
  • 2. Find k if x - 1 is factor of 4x^3 + 3x^2 - 4x + k.
  • 3. Factorize using factor theorem: x^3 - 23x^2 + 142x - 120.
  • 4. Determine whether 2x + 1 is factor of 4x^3 + 4x^2 - x - 1.

Model B: Advanced Cubic Algebraic Identities

Definition: Factorization and expansion formulas for cubes of binomials and trinomials.

If a + b + c = 0, then a^3 + b^3 + c^3 = 3abc

Shortcut Trick: When evaluating sum of cubes where base sum is zero, apply the 3abc shortcut directly.

Examples & Explanations:

  • Example 1: Evaluate 28^3 - 15^3 - 13^3 without direct cubing.
    Explanation: 28 + (-15) + (-13) = 0. Result = 3(28)(-15)(-13) = 16380.
  • Example 2: Expand (2x + y + z)^2.
    Explanation: 4x^2 + y^2 + z^2 + 4xy + 2yz + 4zx.

Homework Problems:

  • 1. Evaluate: (-12)^3 + (7)^3 + (5)^3.
  • 2. If x + y + z = 10 and xy + yz + zx = 31, find x^3 + y^3 + z^3 - 3xyz.
  • 3. Factorize: 27x^3 + y^3 + z^3 - 9xyz.
  • 4. Expand: (3a - 2b - c)^2.

Model A: Distance & Midpoint Formulas

Definition: Cartesian coordinate geometry formulas for distance between points and line segment midpoints.

d = sqrt((x2 - x1)^2 + (y2 - y1)^2), Midpoint = ((x1+x2)/2, (y1+y2)/2)

Shortcut Trick: To check if three points form a right-angled triangle, verify Pythagoras theorem on squared distances between vertices.

Examples & Explanations:

  • Example 1: Distance between (2, 3) and (5, 7).
    Explanation: sqrt(3^2 + 4^2) = 5.
  • Example 2: Find midpoint of segment joining (-1, 7) and (4, -3).
    Explanation: ((-1+4)/2, (7-3)/2) = (1.5, 2).

Homework Problems:

  • 1. Check whether points (1, 5), (2, 3) and (-2, -11) are collinear.
  • 2. Find point on y-axis equidistant from (6, 5) and (-4, 3).
  • 3. Show that points (1, 7), (4, 2), (-1, -1), (-4, 4) form a square.
  • 4. Find centroid of triangle with vertices (1, 4), (3, -2), (5, 2).

Model B: Section Formula & Triangle Area

Definition: Formulas for dividing line segments in specific ratios and calculating coordinate triangle areas.

Section Formula: ((m1x2 + m2x1)/(m1+m2), (m1y2 + m2y1)/(m1+m2))

Shortcut Trick: Area of triangle with one vertex at origin (0,0), (x1, y1), and (x2, y2) is given by 0.5 x abs(x1*y2 - x2*y1).

Examples & Explanations:

  • Example 1: Find point dividing join of (-1, 7) and (4, -3) in ratio 2:3.
    Explanation: x = (2(4) + 3(-1))/5 = 1. y = (2(-3) + 3(7))/5 = 3. Point: (1, 3).
  • Example 2: Area of triangle with vertices (0,0), (3,4), and (5,12).
    Explanation: 0.5 x abs(3(12) - 5(4)) = 8.

Homework Problems:

  • 1. Find coordinates of point dividing join of (4, -3) and (8, 5) in ratio 3:1 internally.
  • 2. Find ratio in which y-axis divides line segment joining (-4, 5) and (3, -7).
  • 3. Find area of triangle with vertices (1, 2), (4, 6), (3, 5).
  • 4. Find k if points (2, -2), (3, k) and (11, 4) are collinear.

Model A: Linear Equations Graphing & Intercepts

Definition: Equations of form ax + by + c = 0 representing straight lines on Cartesian plane with infinite solutions.

Slope m = -a/b, Intercept form: x/a + y/b = 1

Shortcut Trick: To find x-intercept, put y = 0; to find y-intercept, put x = 0.

Examples & Explanations:

  • Example 1: Find slope and y-intercept of 3x + 4y - 12 = 0.
    Explanation: Slope m = -3/4. y-intercept = 3.
  • Example 2: Find intercepts of 4x + 3y = 12.
    Explanation: x-intercept = 3. y-intercept = 4.

Homework Problems:

  • 1. Draw graph of x + y = 4 and find area enclosed with axes.
  • 2. Find coordinates where line 3x - 4y = 12 intersects axes.
  • 3. Find slope of line passing through (2, 3) and (4, 7).
  • 4. Express y = 3x - 5 in standard form and find a, b, c.

Model B: Word Problems & Solutions Set

Definition: Finding coordinate pairs satisfying two-variable linear equations and modeling real-world constraints.

Infinitely many solutions exist for linear equation in two variables.

Shortcut Trick: Equation of line parallel to x-axis is y = k; parallel to y-axis is x = k.

Examples & Explanations:

  • Example 1: Find value of k if x = 2, y = 1 is solution of 2x + 3y = k.
    Explanation: 2(2) + 3(1) = 7. k = 7.
  • Example 2: Write four solutions for 2x + y = 7.
    Explanation: (0,7), (1,5), (2,3), (3,1).

Homework Problems:

  • 1. Give equation of two lines passing through (2, 14). How many such lines are there?
  • 2. If work done by body on application of constant force is directly proportional to distance traveled, express this as linear equation in two variables and draw graph for constant force of 5 units.
  • 3. Check which of following are solutions of equation x - 2y = 4: (0, 2), (2, 0), (4, 0), (sqrt(2), 4*sqrt(2)).
  • 4. Find k if x = 1, y = 2 is solution of equation (3k + 2)x - (4k - 1)y = 2k - 1.

Model A: Euclid's Axioms & Postulates

Definition: Axioms (universal truths) and postulates (geometric assumptions) governing ancient geometry.

Things which are equal to the same thing are equal to one another.

Shortcut Trick: Euclid's Fifth Postulate: If a straight line falling on two straight lines makes interior angles on the same side less than two right angles, the two straight lines, if produced indefinitely, meet on that side.

Examples & Explanations:

  • Example 1: If a = b and b = c, then a = c. Which axiom?
    Explanation: Transitive property / Axiom 1.
  • Example 2: How many lines pass through two distinct points?
    Explanation: Exactly one unique line (Postulate 1).

Homework Problems:

  • 1. State Euclid's fifth postulate and its implications for parallel lines.
  • 2. Differentiate clearly between axioms and postulates with examples.
  • 3. If a point C lies between two points A and B such that AC = BC, prove that AC = 0.5 AB.
  • 4. Explain why axiom "The whole is greater than the part" holds universally.

Model B: Equivalent Versions & Proof Fundamentals

Definition: Playfair's axiom and logical deduction of geometric theorems from postulates.

Playfair's Axiom: Through a given point not on a line, exactly one line can be drawn parallel to the given line.

Shortcut Trick: Two distinct intersecting lines cannot be parallel to the same line.

Examples & Explanations:

  • Example 1: Verify Playfair's axiom in a Cartesian plane.
    Explanation: For point (2,3) and line y = 2x, unique parallel line is y = 2x - 1.
  • Example 2: Prove that all right angles are equal to one another.
    Explanation: Postulate 4 confirmation.

Homework Problems:

  • 1. State Playfair's Axiom and explain its equivalence to Euclid's fifth postulate.
  • 2. Prove that if two lines intersect each other, vertically opposite angles are equal using axioms.
  • 3. If line l is parallel to m and m parallel to n, prove l is parallel to n using geometry axioms.
  • 4. Construct proof for proposition that equilateral triangles can be drawn on any line segment.

Model A: Triangle Congruency Criteria (SAS, ASA, SSS, RHS)

Definition: Conditions under which two triangles are identical in shape and size.

Congruency Criteria: SAS, ASA, AAS, SSS, RHS

Shortcut Trick: In isosceles triangles, angles opposite to equal sides are equal, and vice versa.

Examples & Explanations:

  • Example 1: In triangle ABC, AB = AC and angle B = 50 degrees. Find angle A.
    Explanation: Angle C = 50. Angle A = 180 - 100 = 80 degrees.
  • Example 2: Exterior angle is 120 degrees, interior opposite angles ratio 1:2. Find angles.
    Explanation: x + 2x = 120 implies x = 40. Angles: 40, 80, 60 degrees.

Homework Problems:

  • 1. Prove that angles opposite to equal sides of isosceles triangle are equal.
  • 2. ABC is isosceles with AB = AC. BA produced to D so AD = AB. Show angle BCD is 90 degrees.
  • 3. D and E are points on BC such that BD = CE and AD = AE. Show triangle ABD congruent to triangle ACE.
  • 4. Prove that sum of any two sides of triangle is greater than third side.

Model B: Inequalities in Triangles & Circumcenter Property

Definition: Properties relating greater sides to greater opposite angles in triangles.

In any triangle, side opposite to larger angle is longer.

Shortcut Trick: In a right-angled triangle, the midpoint of the hypotenuse is equidistant from all three vertices.

Examples & Explanations:

  • Example 1: In triangle ABC, angle A = 60 degrees and angle B = 70 degrees. Which side is longest?
    Explanation: Angle C = 50 degrees. Largest angle is B (70), so opposite side AC is longest.
  • Example 2: Right-angled triangle hypotenuse is 10cm. Find distance of midpoint of hypotenuse from vertices.
    Explanation: 5cm.

Homework Problems:

  • 1. Prove that in a right-angled triangle, hypotenuse is longest side.
  • 2. ABC is triangle in which D is any point on side BC. Show that AB + BC + CA > 2AD.
  • 3. In triangle ABC, angle B = 35 degrees and angle C = 65 degrees. Name shortest and longest sides.
  • 4. Prove that sum of three altitudes of triangle is less than sum of its three sides.

Model A: Parallelograms Properties & Midpoint Theorem

Definition: Properties of parallelograms and the theorem regarding line segments joining side midpoints.

Midpoint Theorem: Segment joining midpoints of two sides of triangle is parallel to third side and half of it.

Shortcut Trick: Diagonals of a parallelogram bisect each other; each diagonal divides parallelogram into two congruent triangles.

Examples & Explanations:

  • Example 1: Diagonals of parallelogram bisect each other. If diagonal is 12cm, find segment to center.
    Explanation: 6cm.
  • Example 2: Triangle sides are 10, 12, 14. Find perimeter of triangle formed by joining midpoints.
    Explanation: Perimeter is half of original triangle = 18cm.

Homework Problems:

  • 1. Prove that diagonals of rectangle are equal and bisect each other.
  • 2. Prove Midpoint Theorem for triangles.
  • 3. Show that quadrilateral formed by joining midpoints of consecutive sides of rectangle is a rhombus.
  • 4. ABC is triangle right-angled at C. Line through midpoint M of hypotenuse AB parallel to BC intersects AC at D. Show MD = 0.5 BC.

Model B: Area Theorems of Parallelograms & Triangles

Definition: Theorems concerning figures on the same base and between the same parallels.

Triangles on same base and between same parallels are equal in area.

Shortcut Trick: Area of a triangle is half the area of a parallelogram on the same base and between the same parallels.

Examples & Explanations:

  • Example 1: Triangle and parallelogram on same base and between same parallels. Area ratio?
    Explanation: 1:2.
  • Example 2: Median of triangle divides it into two triangles of...
    Explanation: Equal area.

Homework Problems:

  • 1. Prove that triangles on same base and between same parallels are equal in area.
  • 2. E, F, G, H are midpoints of sides of parallelogram ABCD. Show area of EFGH is half of ABCD.
  • 3. Diagonal AC and BD of quadrilateral ABCD intersect at O such that ar(AOD) = ar(BOC). Prove ABCD is trapezium.
  • 4. If median of triangle ABC intersects at D, prove ar(ABD) = ar(ADC) = 0.5 ar(ABC).

Model A: Circle Theorems & Cyclic Quadrilaterals

Definition: Angles subtended by arcs, cyclic quadrilaterals opposite sum, and perpendicular from center to chord.

Angle at center = 2 x Angle at circumference. Opposite angles of cyclic quadrilateral sum to 180 degrees.

Shortcut Trick: Perpendicular drawn from center of circle to a chord bisects the chord.

Examples & Explanations:

  • Example 1: Angle at center is 100 degrees. Find angle at circumference by same arc.
    Explanation: 100 / 2 = 50 degrees.
  • Example 2: Cyclic quadrilateral has opposite angles (2x - 10) and (3x + 20). Find x.
    Explanation: (2x - 10) + (3x + 20) = 180 implies x = 34.

Homework Problems:

  • 1. Prove that angle in semicircle is a right angle.
  • 2. Chord of length 16cm is at distance of 6cm from center of circle. Find radius of circle.
  • 3. If cyclic quadrilateral ABCD has angle A = 70 degrees, find angle C.
  • 4. Two circles intersect at A and B. AD and AC are diameters. Prove B lies on line segment DC.

Model B: Heron's Formula for Triangle Area

Definition: Calculating area of triangles given lengths of all three sides without altitude.

Area = sqrt(s(s-a)(s-b)(s-c)) where s = (a+b+c)/2

Shortcut Trick: For equilateral triangles of side a, area simplifies to (sqrt(3)/4) x a^2.

Examples & Explanations:

  • Example 1: Find area of triangle with sides 13, 14, 15.
    Explanation: s = 21. Area = sqrt(21 x 8 x 7 x 6) = 84.
  • Example 2: Find area of equilateral triangle of side 8cm.
    Explanation: (sqrt(3)/4) x 64 = 16 x sqrt(3) cm^2.

Homework Problems:

  • 1. Find area of triangle with sides 9cm, 12cm, 15cm using Heron's formula.
  • 2. Sides of triangular plot are in ratio 3:5:7 and perimeter is 300m. Find area.
  • 3. Find area of equilateral triangle whose perimeter is 60cm.
  • 4. Triangular park has sides 120m, 80m, and 50m. Find cost of fencing with wire at 20 units/m leaving 3m gate.

Class 10 Foundation Modules (IIT/JEE Advanced - All Chapters & Complete Models)

Model A: Real Numbers & Euclid's Division Lemma

Definition: Euclid's division lemma (a = bq + r) and Fundamental Theorem of Arithmetic for prime factorization.

HCF(a,b) x LCM(a,b) = a x b

Shortcut Trick: A rational number p/q has terminating decimal expansion if prime factorization of denominator q is of form 2^n x 5^m.

Examples & Explanations:

  • Example 1: Find HCF of 306 and 657 given LCM is 22338.
    Explanation: (306 x 657) / 22338 = 9.
  • Example 2: Check if 17/8 has terminating decimal expansion.
    Explanation: Denominator 8 = 2^3 (only powers of 2 and 5), so it terminates.

Homework Problems:

  • 1. Prove that 3 + 2*sqrt(5) is irrational.
  • 2. Use Euclid's division algorithm to find HCF of 135 and 225.
  • 3. Check if 13/3125 terminates or non-terminating repeating.
  • 4. Prove that square of any positive integer is either of form 3m or 3m + 1 for some integer m.

Model B: Polynomials Zeroes & Coefficients Relationships

Definition: Relationships between zeroes and coefficients of quadratic and cubic polynomials.

Quadratic: Sum = -b/a, Product = c/a. Cubic: Sum = -b/a, Sum of products = c/a, Product = -d/a.

Shortcut Trick: To construct cubic polynomial given roots alpha, beta, gamma: x^3 - (sum)x^2 + (sum of products)x - (product) = 0.

Examples & Explanations:

  • Example 1: Find zeroes of x^2 - 2x - 8 and verify relationship.
    Explanation: Zeroes: 4 and -2. Sum = 2, Product = -8.
  • Example 2: Quadratic polynomial with sum of zeroes 4 and product 1.
    Explanation: x^2 - 4x + 1 = 0.

Homework Problems:

  • 1. Find zeroes of quadratic polynomial 6x^2 - 3 - 7x and verify relationship between zeroes and coefficients.
  • 2. If alpha and beta are zeroes of 2x^2 - 7x + 3, find alpha^2 + beta^2.
  • 3. Find cubic polynomial whose zeroes are 3, -1, and -1/3.
  • 4. If sum and product of zeroes of quadratic polynomial are sqrt(2) and 1/3 respectively, find polynomial.

Model A: Pair of Linear Equations Consistency & Solving

Definition: Consistency conditions for two-variable linear equations (unique, infinite, or no solution).

Unique: a1/a2 not equal to b1/b2, Infinite: a1/a2 = b1/b2 = c1/c2, No solution: a1/a2 = b1/b2 not equal to c1/c2

Shortcut Trick: Cross-multiplication formula for a1*x + b1*y + c1 = 0 and a2*x + b2*y + c2 = 0.

Examples & Explanations:

  • Example 1: Find k for which 2x + 3y = 7 and (k-1)x + (k+1)y = 3k + 1 have infinite solutions.
    Explanation: 2/(k-1) = 3/(k+1) = 7/(3k+1). Solving gives k = 5.
  • Example 2: Solve x + y = 5 and 2x - 3y = 4.
    Explanation: x = 3.8, y = 1.2.

Homework Problems:

  • 1. For what values of k will the pair of equations 3x + y = 1 and (2k - 1)x + (k - 1)y = 2k + 1 have no solution?
  • 2. Solve pair: 2x + 3y = 11 and 2x - 4y = -24 using substitution or elimination.
  • 3. Boat goes 30km upstream and 44km downstream in 10 hours. In 13 hours, it can go 40km upstream and 55km downstream. Find stream speed.
  • 4. Solve for x and y: x/a + y/b = 2 and ax - by = a^2 - b^2.

Model B: Quadratic Equations Discriminant & Roots Nature

Definition: Solving quadratic equations using discriminant formula and factoring.

Discriminant D = b^2 - 4ac, x = (-b plus or minus sqrt(D)) / (2a)

Shortcut Trick: If D > 0, real and distinct roots; if D = 0, real and equal roots; if D < 0, non-real complex roots.

Examples & Explanations:

  • Example 1: Find discriminant of 2x^2 - 4x + 3 = 0 and state nature of roots.
    Explanation: D = 16 - 24 = -8 (< 0), non-real complex conjugates.
  • Example 2: Find k for which kx(x - 2) + 6 = 0 has equal roots.
    Explanation: kx^2 - 2kx + 6 = 0. D = 4k^2 - 24k = 0 implies k = 6.

Homework Problems:

  • 1. Find values of k for which quadratic equation kx(x - 2) + 6 = 0 has two real and equal roots.
  • 2. Solve for x: 1/(x+4) - 1/(x-7) = 11/30.
  • 3. If alpha and beta are roots of 3x^2 - 5x + 2 = 0, find alpha^3 + beta^3.
  • 4. Find quadratic equation whose roots are reciprocal to roots of 2x^2 - 3x - 5 = 0.

Model A: Arithmetic Progressions (AP) Formulas & Sums

Definition: Sequences with constant common difference d (a_n = a + (n-1)d).

Sum of n terms S_n = (n/2)[2a + (n-1)d] = (n/2)(a + l)

Shortcut Trick: If sum of first n terms of an AP is S_n = An^2 + Bn, common difference d = 2A and first term a = A + B.

Examples & Explanations:

  • Example 1: Find 10th term of AP: 2, 7, 12, ...
    Explanation: 2 + 9(5) = 47.
  • Example 2: If sum of first n terms is S_n = 3n^2 + 5n, find common difference.
    Explanation: Coefficient of n^2 is 3, so d = 2(3) = 6.

Homework Problems:

  • 1. Which term of AP 3, 15, 27, 39 is 132 more than its 54th term?
  • 2. Find sum of all odd integers between 1 and 1000.
  • 3. If sum of first n terms of AP is 4n - n^2, find first term and sum of first 2 terms.
  • 4. Sum of 4th and 8th terms of AP is 24 and sum of 6th and 10th terms is 44. Find first three terms.

Model B: Geometric Progressions (GP) & Advanced Progressions

Definition: Sequences with constant common ratio r (a_n = a x r^(n-1)).

GP Sum S_n = a(r^n - 1) / (r - 1) (for r > 1)

Shortcut Trick: If a, b, c are in AP, then 2b = a + c. If in GP, b^2 = ac.

Examples & Explanations:

  • Example 1: Find 7th term of GP: 2, 6, 18, ...
    Explanation: a = 2, r = 3. a_7 = 2(3^6) = 1458.
  • Example 2: Find geometric mean of 4 and 9.
    Explanation: sqrt(4 x 9) = 6.

Homework Problems:

  • 1. Which term of GP 2, 2*sqrt(2), 4, ... is 128?
  • 2. Find sum of first 8 terms of GP: 1, 2, 4, 8, ...
  • 3. If 3rd term of GP is 24 and 6th term is 192, find 10th term.
  • 4. Find three numbers in AP whose sum is 24 and product is 440.

Model A: Triangles Similarity & Thales Theorem (BPT)

Definition: Basic Proportionality Theorem (Thales theorem) and triangle similarity criteria (AAA, SSS, SAS).

Thales Theorem: If line is drawn parallel to one side of triangle intersecting other two sides, it divides them in same ratio.

Shortcut Trick: Ratio of areas of two similar triangles equals square of ratio of their corresponding sides.

Examples & Explanations:

  • Example 1: Sides of two similar triangles are in ratio 2:3. Find area ratio.
    Explanation: (2/3)^2 = 4:9.
  • Example 2: Triangle ABC has DE parallel to BC with AD = 2cm, DB = 3cm, AE = 4cm. Find EC.
    Explanation: 2/3 = 4/EC implies EC = 6cm.

Homework Problems:

  • 1. Prove Basic Proportionality Theorem (Thales Theorem).
  • 2. Prove that ratio of areas of two similar triangles is equal to square of ratio of their corresponding sides.
  • 3. Diagonals of trapezium ABCD intersect each other at point O. Prove AO/BO = CO/DO.
  • 4. Vertical stick of length 6m casts shadow 4m long on ground at same time tower casts shadow 28m long. Find tower height.

Model B: Advanced Coordinate Geometry Applications

Definition: Collinearity conditions, centroid formulas, and triangle area proofs.

Area of triangle = 0.5 x abs(x1(y2-y3) + x2(y3-y1) + x3(y1-y2))

Shortcut Trick: Three points are collinear if and only if the coordinate triangle area formed by them is identically zero.

Examples & Explanations:

  • Example 1: Triangle area with vertices (2, 3), (-1, 0), (2, -4).
    Explanation: 0.5 x abs(2(0 - (-4)) + (-1)(-4 - 3) + 2(3 - 0)) = 10.5.
  • Example 2: Find centroid of triangle with vertices (1, 4), (3, -2), (5, 2).
    Explanation: (3, 4/3).

Homework Problems:

  • 1. Find value of k for which points (7, -2), (5, 1), (3, k) are collinear.
  • 2. Find area of triangle formed by joining midpoints of sides of triangle with vertices (0, -1), (2, 1) and (0, 3). Find ratio of this area to given triangle area.
  • 3. Find coordinates of points which divide line segment joining A(-2, 2) and B(2, 8) into four equal parts.
  • 4. If A(6, 1), B(8, 2), C(9, 4) and D(p, 3) are vertices of parallelogram taken in order, find p.

Model A: Trigonometric Identities & Standard Ratios

Definition: Trigonometric ratios in right triangles and fundamental Pythagorean identities.

sin^2(theta) + cos^2(theta) = 1, 1 + tan^2(theta) = sec^2(theta), 1 + cot^2(theta) = csc^2(theta)

Shortcut Trick: For complementary angle conversions: sin(90 - theta) = cos(theta), tan(90 - theta) = cot(theta).

Examples & Explanations:

  • Example 1: Prove (sin - 2*sin^3)/(2*cos^3 - cos) = tan.
    Explanation: Factor out sine and cosine, substitute cos^2 = 1 - sin^2 to cancel terms.
  • Example 2: Evaluate sin(25)cos(65) + cos(25)sin(65).
    Explanation: sin^2(25) + cos^2(25) = 1.

Homework Problems:

  • 1. Prove identity: sqrt((1 + sin)/(1 - sin)) = sec + tan.
  • 2. Prove: (sin - 2*sin^3)/(2*cos^3 - cos) = tan.
  • 3. Evaluate: (sin 30 + tan 45 - csc 60) / (sec 30 + cos 60 + cot 45).
  • 4. If tan + sin = m and tan - sin = n, prove m^2 - n^2 = 4*sqrt(mn).

Model B: Heights and Distances (Angle of Elevation/Depression)

Definition: Solving height and distance word problems using trigonometric ratios.

tan(theta) = Perpendicular / Base

Shortcut Trick: Tower shadow problem: If angles of elevation from distances a and b are complementary, tower height h = sqrt(ab).

Examples & Explanations:

  • Example 1: Find tower height if angles of elevation from distances 4m and 9m are complementary.
    Explanation: h = sqrt(4 x 9) = 6m.
  • Example 2: Observer 1.5m tall is 28.5m away from chimney. Angle of elevation is 45 degrees. Find height.
    Explanation: Height = 1.5 + 28.5 = 30m.

Homework Problems:

  • 1. A 1.2m tall girl spots a balloon moving with wind in horizontal line at height 88.2m. Angle of elevation from her eyes is 60 degrees, which reduces to 30 degrees later. Find distance traveled by balloon.
  • 2. Tower standing on level ground is surmounted by vertical flag staff of height 5m. From point on ground, angle of elevation of bottom and top of flag staff are 30 degrees and 60 degrees. Find tower height.
  • 3. Angle of elevation of top of building from foot of tower is 30 degrees and angle of elevation of top of tower from foot of building is 60 degrees. If tower is 50m high, find building height.
  • 4. Two poles of equal heights are standing opposite each other on either side of road which is 80m wide. From point between them on road, angles of elevation of top of poles are 60 degrees and 30 degrees. Find height of poles and distances of point from poles.

Model A: Tangents to a Circle Theorems

Definition: Tangent is perpendicular to radius at point of contact; lengths of tangents from external point are equal.

Angle between two tangents from external point P = 180 degrees - Angle subtended at center

Shortcut Trick: If circle is inscribed inside a quadrilateral, sum of opposite sides is equal (AB + CD = AD + BC).

Examples & Explanations:

  • Example 1: Tangent from Q is 24cm, distance from center is 25cm. Find radius.
    Explanation: sqrt(25^2 - 24^2) = 7cm.
  • Example 2: Two concentric circles radii 5cm and 3cm. Find chord length of larger touching smaller.
    Explanation: 2 x sqrt(5^2 - 3^2) = 8cm.

Homework Problems:

  • 1. Prove that tangents drawn at ends of diameter of circle are parallel.
  • 2. Quadrilateral ABCD circumscribes circle. Prove AB + CD = AD + BC.
  • 3. Prove that parallelogram circumscribing a circle is a rhombus.
  • 4. If tangents PA and PB from P to circle center O are inclined at 80 degrees, find angle POA.

Model B: Areas Related to Circles & Sectors

Definition: Areas of circles, sectors, segments, and combinations of plane figures.

Sector Area = (theta / 360) x pi x r^2, Arc Length = (theta / 360) x 2 x pi x r

Shortcut Trick: Area of segment = Area of sector - Area of corresponding triangle (0.5 x r^2 x sin(theta)).

Examples & Explanations:

  • Example 1: Find area of sector of circle with radius 6cm and angle 60 degrees.
    Explanation: (60/360) x (22/7) x 36 = 132/7 cm^2.
  • Example 2: Minute hand of clock is 10cm long. Area swept in 6 minutes?
    Explanation: Angle in 6 mins = 36 degrees. Area = 10 x pi cm^2.

Homework Problems:

  • 1. Find area of sector of circle with radius 14cm and angle 45 degrees.
  • 2. Chord of circle of radius 10cm subtends right angle at center. Find areas of corresponding minor and major segments (pi = 3.14).
  • 3. Wheel of car has diameter 80cm each. How many complete revolutions does each wheel make in 10 minutes when car is traveling at 66 km/h?
  • 4. Find area of shaded region in square of side 14cm where four semicircles are drawn on each side as diameter.

Model A: Grouped Data Statistics (Mean, Median, Mode)

Definition: Calculating central tendency measures for continuous grouped frequency distributions.

Mean = sum(f_i x_i) / sum(f_i), Median = l + ((N/2 - cf)/f) x h

Shortcut Trick: Empirical relationship connecting three measures: 3 x Median = Mode + 2 x Mean.

Examples & Explanations:

  • Example 1: If mean is 25 and median is 24, find mode using empirical formula.
    Explanation: Mode = 3(24) - 2(25) = 22.
  • Example 2: Find class mark of interval 20-30.
    Explanation: (20 + 30) / 2 = 25.

Homework Problems:

  • 1. Find mean of grouped distribution for intervals 0-10 (freq 3), 10-20 (freq 5), 20-30 (freq 8), 30-40 (freq 3), 40-50 (freq 1).
  • 2. Find median of grouped frequency distribution where N=50, cumulative frequency before median class is 22, frequency is 12, class size 10, lower limit 20.
  • 3. If mode of distribution is 45 and mean is 27, find median using empirical relation.
  • 4. The median of following data is 525. Find values of x and y if total frequency is 100 with intervals 0-100 (2), 100-200 (5), 200-300 (x), 300-400 (12), 400-500 (17), 500-600 (20), 600-700 (y), 700-800 (9), 800-900 (7), 900-1000 (4).

Model B: Classical Probability & Card/Dice Problems

Definition: Measuring likelihood of events based on ratio of favorable outcomes to total equally likely outcomes.

P(E) = Favorable Outcomes / Total Outcomes, P(E) + P(not E) = 1

Shortcut Trick: For rolling two dice simultaneously, maximum sum is 12 and most frequent sum is 7 (appearing 6 times out of 36 outcomes).

Examples & Explanations:

  • Example 1: Probability of getting red face card from 52 cards deck.
    Explanation: 6 / 52 = 3 / 26.
  • Example 2: Two dice thrown simultaneously, probability of getting sum of 8.
    Explanation: Favorable pairs: (2,6), (3,5), (4,4), (5,3), (6,2) -> 5/36.

Homework Problems:

  • 1. Box contains 5 red marbles, 8 white marbles, 4 green marbles. Probability that drawn marble is not green?
  • 2. From pack of 52 cards, all face cards removed. Find probability of drawing black ace.
  • 3. Two coins tossed simultaneously. Find probability of getting at least one head.
  • 4. Die is thrown twice. What is probability that 5 will not come up either time?