Grade 7 · Maths · curriculum collection
Grade 7 Maths, Common Core domains
8 units for Grade 7 maths, organised by Common Core domain: Ratios and Proportional Relationships, The Number System, Expressions and Equations, Geometry, Statistics and Probability. Each unit has a short lesson, a practice worksheet and a review worksheet, both with answer keys.
Answer-checked and approved on 29 October 2026
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Aligned by StudyBrix at domain level. Not an official publication of, or endorsed by, the standards' authors. Framework: Common Core State Standards for Mathematics.
Units in teaching order
7.RP Ratios and Proportional Relationships
Percentages
Percent of a quantity, percent change, successive percent changes and finding the whole from a percent.
Short lesson: Find the original whole
Study guide for Grades 6 to 9: 2 worked examples and 2 practice questions. Divide by the percentage as a decimal, not by the whole-number percent.
whole = part ÷ (p/100)
Divide by the percentage as a decimal, not by the whole-number percent.
Worked example
40% of a number is 392. What is the number?
392 ÷ 0.4 = 980
Answer: 980
Worksheets
A practice worksheet and a review worksheet, 12 and 12 questions.
Practice worksheet: 12 questions
Find 56% of 300.
A value increases from 140 to 191.8. What is the percentage increase?
A quantity starts at 1600, increases by 50%, then decreases by 40%. Find the final quantity.
10% of a number is 14. What is the number?
Find 69% of 680.
A value increases from 610 to 695.4. What is the percentage increase?
A quantity starts at 4200, increases by 50%, then decreases by 20%. Find the final quantity.
25% of a number is 290. What is the number?
Find 12% of 760.
A value increases from 640 to 665.6. What is the percentage increase?
A quantity starts at 7500, increases by 20%, then decreases by 10%. Find the final quantity.
50% of a number is 550. What is the number?
Answer key
- 168 56/100 × 300 = 168
- 37 % (191.8 − 140) ÷ 140 × 100 = 37%
- 1440 1600 × 1.5 × 0.6 = 1440
- 140 14 ÷ 0.1 = 140
- 469.2 69/100 × 680 = 469.2
- 14 % (695.4 − 610) ÷ 610 × 100 = 14%
- 5040 4200 × 1.5 × 0.8 = 5040
- 1160 290 ÷ 0.25 = 1160
- 91.2 12/100 × 760 = 91.2
- 4 % (665.6 − 640) ÷ 640 × 100 = 4%
- 8100 7500 × 1.2 × 0.9 = 8100
- 1100 550 ÷ 0.5 = 1100
Review worksheet: 12 questions
A quantity starts at 3500, increases by 10%, then decreases by 25%. Find the final quantity.
Find 19% of 470.
A value increases from 160 to 187.2. What is the percentage increase?
75% of a number is 795. What is the number?
A quantity starts at 300, increases by 50%, then decreases by 40%. Find the final quantity.
Find 26% of 430.
A value increases from 780 to 959.4. What is the percentage increase?
50% of a number is 300. What is the number?
A quantity starts at 1000, increases by 25%, then decreases by 10%. Find the final quantity.
Find 15% of 350.
A value increases from 680 to 863.6. What is the percentage increase?
10% of a number is 56. What is the number?
Answer key
- 2887.5 3500 × 1.1 × 0.75 = 2887.5
- 89.3 19/100 × 470 = 89.3
- 17 % (187.2 − 160) ÷ 160 × 100 = 17%
- 1060 795 ÷ 0.75 = 1060
- 270 300 × 1.5 × 0.6 = 270
- 111.8 26/100 × 430 = 111.8
- 23 % (959.4 − 780) ÷ 780 × 100 = 23%
- 600 300 ÷ 0.5 = 600
- 1125 1000 × 1.25 × 0.9 = 1125
- 52.5 15/100 × 350 = 52.5
- 27 % (863.6 − 680) ÷ 680 × 100 = 27%
- 560 56 ÷ 0.1 = 560
7.RP Ratios and Proportional Relationships
Ratio and proportion problems
Proportional relationships and sharing in a ratio.
Short lesson: Equations, expressions and equivalent steps
Study guide for Grades 6 to 9: 4 key ideas, including expression or equation, balance and distribute; 2 worked examples and 3 practice questions. Preserve equality and check a solution in the original equation.
- Expression or equation. An expression represents a value; an equation asserts equality between two expressions.
- Balance. Applying the same valid operation to both sides preserves an equation. Division by zero is never valid.
- Distribute. a(b + c) = ab + ac. The multiplier acts on every term inside the brackets.
- Check. Substitute a proposed solution into the original equation, not just a rearranged line.
Worked example
Which item is an equation?
The equals sign asserts that two expressions have equal values.
Answer: 3x + 2 = 11
Worksheets
A practice worksheet and a review worksheet, 12 and 12 questions.
Practice worksheet: 12 questions
Split 196 in the ratio 5:2. What is the first share?
y = kx. When x = 22, y = 264. Find y when x = 57.
Split 80 in the ratio 11:9. What is the first share?
y = kx. When x = 26, y = 78. Find y when x = 59.
Split 88 in the ratio 4:7. What is the first share?
y = kx. When x = 28, y = 252. Find y when x = 73.
Split 72 in the ratio 10:8. What is the first share?
y = kx. When x = 14, y = 112. Find y when x = 50.
Split 400 in the ratio 9:7. What is the first share?
y = kx. When x = 14, y = 112. Find y when x = 55.
Split 117 in the ratio 9:4. What is the first share?
y = kx. When x = 2, y = 14. Find y when x = 58.
Answer key
- 140 196 ÷ (5 + 2) = 28; 5 × 28 = 140
- 684 k = 264/22 = 12; y = 12 × 57 = 684
- 44 80 ÷ (11 + 9) = 4; 11 × 4 = 44
- 177 k = 78/26 = 3; y = 3 × 59 = 177
- 32 88 ÷ (4 + 7) = 8; 4 × 8 = 32
- 657 k = 252/28 = 9; y = 9 × 73 = 657
- 40 72 ÷ (10 + 8) = 4; 10 × 4 = 40
- 400 k = 112/14 = 8; y = 8 × 50 = 400
- 225 400 ÷ (9 + 7) = 25; 9 × 25 = 225
- 440 k = 112/14 = 8; y = 8 × 55 = 440
- 81 117 ÷ (9 + 4) = 9; 9 × 9 = 81
- 406 k = 14/2 = 7; y = 7 × 58 = 406
Review worksheet: 12 questions
y = kx. When x = 29, y = 435. Find y when x = 77.
Split 56 in the ratio 6:2. What is the first share?
y = kx. When x = 17, y = 221. Find y when x = 40.
Split 204 in the ratio 8:9. What is the first share?
y = kx. When x = 7, y = 91. Find y when x = 43.
Split 176 in the ratio 7:9. What is the first share?
y = kx. When x = 12, y = 144. Find y when x = 38.
Split 95 in the ratio 12:7. What is the first share?
y = kx. When x = 27, y = 243. Find y when x = 58.
Split 500 in the ratio 8:12. What is the first share?
y = kx. When x = 9, y = 45. Find y when x = 86.
Split 234 in the ratio 2:7. What is the first share?
Answer key
- 1155 k = 435/29 = 15; y = 15 × 77 = 1155
- 42 56 ÷ (6 + 2) = 7; 6 × 7 = 42
- 520 k = 221/17 = 13; y = 13 × 40 = 520
- 96 204 ÷ (8 + 9) = 12; 8 × 12 = 96
- 559 k = 91/7 = 13; y = 13 × 43 = 559
- 77 176 ÷ (7 + 9) = 11; 7 × 11 = 77
- 456 k = 144/12 = 12; y = 12 × 38 = 456
- 60 95 ÷ (12 + 7) = 5; 12 × 5 = 60
- 522 k = 243/27 = 9; y = 9 × 58 = 522
- 200 500 ÷ (8 + 12) = 25; 8 × 25 = 200
- 430 k = 45/9 = 5; y = 5 × 86 = 430
- 52 234 ÷ (2 + 7) = 26; 2 × 26 = 52
7.NS The Number System
Integer operations
Adding integers, subtracting integers and multiplying integers.
Short lesson: Subtract signed integers
Study guide for Grades 6 to 8: 2 worked examples and 2 practice questions. Subtracting a negative is adding its opposite.
a − b = a + (−b)
Subtracting a negative is adding its opposite.
Worked example
(41) − (-53) = ?
(41) + (53) = 94
Answer: 94
Worksheets
A practice worksheet and a review worksheet, 12 and 12 questions.
Practice worksheet: 12 questions
(-145) + 21 = ?
(-65) − (70) = ?
(-24) × (-10) = ?
(-39) + 44 = ?
(-59) − (-92) = ?
(-21) × (-3) = ?
(-92) + 3 = ?
(-38) − (59) = ?
(-33) × (-6) = ?
(-140) + 6 = ?
(-56) − (32) = ?
(-16) × (-32) = ?
Answer key
- -124 (-145) + 21 = -124
- -135 (-65) + (-70) = -135
- 240 (-24) × (-10) = 240
- 5 (-39) + 44 = 5
- 33 (-59) + (92) = 33
- 63 (-21) × (-3) = 63
- -89 (-92) + 3 = -89
- -97 (-38) + (-59) = -97
- 198 (-33) × (-6) = 198
- -134 (-140) + 6 = -134
- -88 (-56) + (-32) = -88
- 512 (-16) × (-32) = 512
Review worksheet: 12 questions
(-41) − (-40) = ?
(-27) + 106 = ?
(-27) × (-19) = ?
(-63) − (-10) = ?
(-21) + 5 = ?
(-15) × (-10) = ?
(-97) − (21) = ?
(-92) + 125 = ?
(-35) × (-34) = ?
(1) − (6) = ?
(-141) + 143 = ?
(-34) × (-32) = ?
Answer key
- -1 (-41) + (40) = -1
- 79 (-27) + 106 = 79
- 513 (-27) × (-19) = 513
- -53 (-63) + (10) = -53
- -16 (-21) + 5 = -16
- 150 (-15) × (-10) = 150
- -118 (-97) + (-21) = -118
- 33 (-92) + 125 = 33
- 1190 (-35) × (-34) = 1190
- -5 (1) + (-6) = -5
- 2 (-141) + 143 = 2
- 1088 (-34) × (-32) = 1088
7.NS The Number System
Dividing fractions
Dividing fractions.
Short lesson: Subtract mixed numbers
Study guide for Grades 4 to 7: 2 worked examples and 2 practice questions. Convert to improper fractions; then subtract with a common denominator.
w a/b = (wb + a)/b
Convert to improper fractions; then subtract with a common denominator.
Worked example
Calculate 7 1/4 − 5 2/4. Give a fraction in simplest form.
(29 − 22)/4 = 7/4
Answer: 7/4
Worksheets
A practice worksheet and a review worksheet, 12 and 12 questions.
Practice worksheet: 12 questions
9/5 ÷ 5/12 = ?
10/20 ÷ 1/12 = ?
6/7 ÷ 2/11 = ?
9/17 ÷ 4/3 = ?
4/10 ÷ 5/3 = ?
11/18 ÷ 5/13 = ?
1/8 ÷ 10/2 = ?
2/17 ÷ 9/18 = ?
12/13 ÷ 4/5 = ?
9/8 ÷ 12/20 = ?
3/2 ÷ 4/17 = ?
1/17 ÷ 5/19 = ?
Answer key
- 108/25 9/5 × 12/5 = 108/25
- 6 10/20 × 12/1 = 6
- 33/7 6/7 × 11/2 = 33/7
- 27/68 9/17 × 3/4 = 27/68
- 6/25 4/10 × 3/5 = 6/25
- 143/90 11/18 × 13/5 = 143/90
- 1/40 1/8 × 2/10 = 1/40
- 4/17 2/17 × 18/9 = 4/17
- 15/13 12/13 × 5/4 = 15/13
- 15/8 9/8 × 20/12 = 15/8
- 51/8 3/2 × 17/4 = 51/8
- 19/85 1/17 × 19/5 = 19/85
Review worksheet: 12 questions
2/15 ÷ 6/10 = ?
12/11 ÷ 10/3 = ?
2/10 ÷ 7/9 = ?
6/17 ÷ 3/15 = ?
3/18 ÷ 12/7 = ?
11/19 ÷ 4/7 = ?
9/7 ÷ 12/7 = ?
9/15 ÷ 3/9 = ?
6/16 ÷ 4/19 = ?
12/17 ÷ 10/8 = ?
9/8 ÷ 12/13 = ?
7/17 ÷ 5/6 = ?
Answer key
- 2/9 2/15 × 10/6 = 2/9
- 18/55 12/11 × 3/10 = 18/55
- 9/35 2/10 × 9/7 = 9/35
- 30/17 6/17 × 15/3 = 30/17
- 7/72 3/18 × 7/12 = 7/72
- 77/76 11/19 × 7/4 = 77/76
- 3/4 9/7 × 7/12 = 3/4
- 9/5 9/15 × 9/3 = 9/5
- 57/32 6/16 × 19/4 = 57/32
- 48/85 12/17 × 8/10 = 48/85
- 39/32 9/8 × 13/12 = 39/32
- 42/85 7/17 × 6/5 = 42/85
7.EE Expressions and Equations
Algebra
Two-step equations, evaluating expressions, one-step equations and combining like terms.
Short lesson: Combine like terms
Study guide for Grades 6 to 9: 2 worked examples and 2 practice questions. Only terms with the same variable part can be combined this way.
ax + bx = (a + b)x
Only terms with the same variable part can be combined this way.
Worked example
Find the coefficient of x after simplifying 32x + 33x.
(32 + 33)x = 65x
Answer: 65
Worksheets
A practice worksheet and a review worksheet, 12 and 12 questions.
Practice worksheet: 12 questions
Solve for x: 10x + 5 = 285
Find the coefficient of x after simplifying 12x + 37x.
Evaluate 5x + 30 when x = 15.
Solve for x: 3x = -81
Solve for x: 20x + 80 = 20
Find the coefficient of x after simplifying 6x + 9x.
Evaluate 5x + 25 when x = -13.
Solve for x: 30x = -90
Solve for x: 3x + 38 = 89
Find the coefficient of x after simplifying 17x + 30x.
Evaluate 6x + 25 when x = -7.
Solve for x: 26x = -494
Answer key
- 28 10x = 285 − 5 = 280; x = 28
- 49 (12 + 37)x = 49x
- 105 5 × (15) + 30 = 105
- -27 x = -81 ÷ 3 = -27
- -3 20x = 20 − 80 = -60; x = -3
- 15 (6 + 9)x = 15x
- -40 5 × (-13) + 25 = -40
- -3 x = -90 ÷ 30 = -3
- 17 3x = 89 − 38 = 51; x = 17
- 47 (17 + 30)x = 47x
- -17 6 × (-7) + 25 = -17
- -19 x = -494 ÷ 26 = -19
Review worksheet: 12 questions
Solve for x: 6x + 28 = -44
Evaluate 4x + 5 when x = 0.
Find the coefficient of x after simplifying 5x + 33x.
Solve for x: 26x = 910
Solve for x: 5x + 47 = 82
Evaluate 15x + 4 when x = 14.
Find the coefficient of x after simplifying 25x + 4x.
Solve for x: 17x = 680
Solve for x: 9x + 49 = 103
Evaluate 8x + 14 when x = 13.
Find the coefficient of x after simplifying 16x + 20x.
Solve for x: 8x = 40
Answer key
- -12 6x = -44 − 28 = -72; x = -12
- 5 4 × (0) + 5 = 5
- 38 (5 + 33)x = 38x
- 35 x = 910 ÷ 26 = 35
- 7 5x = 82 − 47 = 35; x = 7
- 214 15 × (14) + 4 = 214
- 29 (25 + 4)x = 29x
- 40 x = 680 ÷ 17 = 40
- 6 9x = 103 − 49 = 54; x = 6
- 118 8 × (13) + 14 = 118
- 36 (16 + 20)x = 36x
- 5 x = 40 ÷ 8 = 5
7.EE Expressions and Equations
Powers & roots
Whole-number exponents.
Short lesson: Evaluate powers
Study guide for Grades 6 to 9: 2 worked examples and 2 practice questions. The exponent counts factors, not additions.
aⁿ = a × a × … × a (n factors)
The exponent counts factors, not additions.
Worked example
9^5 = ?
9 × 9 × 9 × 9 × 9 = 59049
Answer: 59049
Worksheets
A practice worksheet and a review worksheet, 12 and 12 questions.
Practice worksheet: 12 questions
10^5 = ?
8^4 = ?
7^3 = ?
9^2 = ?
9^3 = ?
8^2 = ?
5^2 = ?
7^2 = ?
2^3 = ?
10^3 = ?
3^2 = ?
12^3 = ?
Answer key
- 100000 10 × 10 × 10 × 10 × 10 = 100000
- 4096 8 × 8 × 8 × 8 = 4096
- 343 7 × 7 × 7 = 343
- 81 9 × 9 = 81
- 729 9 × 9 × 9 = 729
- 64 8 × 8 = 64
- 25 5 × 5 = 25
- 49 7 × 7 = 49
- 8 2 × 2 × 2 = 8
- 1000 10 × 10 × 10 = 1000
- 9 3 × 3 = 9
- 1728 12 × 12 × 12 = 1728
Review worksheet: 12 questions
11^2 = ?
6^3 = ?
12^4 = ?
6^4 = ?
4^2 = ?
11^5 = ?
11^4 = ?
12^2 = ?
9^5 = ?
3^5 = ?
4^5 = ?
5^4 = ?
Answer key
- 121 11 × 11 = 121
- 216 6 × 6 × 6 = 216
- 20736 12 × 12 × 12 × 12 = 20736
- 1296 6 × 6 × 6 × 6 = 1296
- 16 4 × 4 = 16
- 161051 11 × 11 × 11 × 11 × 11 = 161051
- 14641 11 × 11 × 11 × 11 = 14641
- 144 12 × 12 = 144
- 59049 9 × 9 × 9 × 9 × 9 = 59049
- 243 3 × 3 × 3 × 3 × 3 = 243
- 1024 4 × 4 × 4 × 4 × 4 = 1024
- 625 5 × 5 × 5 × 5 = 625
7.G Geometry
Geometry
Area of trapezoids, scale factors and area, circumference of circles and area of circles.
Short lesson: Scale factors and area
Study guide for Grades 7 to 10: 2 worked examples and 2 practice questions. A length scale factor k changes area by k squared.
new area = old area × k²
A length scale factor k changes area by k squared.
Worked example
A shape has area 64 cm². All lengths are multiplied by 2. Find the new area in cm².
64 × 2² = 256
Answer: 256 cm²
Worksheets
A practice worksheet and a review worksheet, 12 and 12 questions.
Practice worksheet: 12 questions
A trapezoid has parallel sides 20 cm and 3 cm and height 7 cm. Find its area in cm².
A shape has area 7 cm². All lengths are multiplied by 9. Find the new area in cm².
A circle has radius 51 cm. Its area is kπ cm². Find k.
A circle has radius 71 cm. Its circumference is kπ cm. Find k.
A trapezoid has parallel sides 30 cm and 2 cm and height 18 cm. Find its area in cm².
A shape has area 24 cm². All lengths are multiplied by 3. Find the new area in cm².
A circle has radius 64 cm. Its area is kπ cm². Find k.
A circle has radius 25 cm. Its circumference is kπ cm. Find k.
A trapezoid has parallel sides 17 cm and 13 cm and height 14 cm. Find its area in cm².
A shape has area 26 cm². All lengths are multiplied by 7. Find the new area in cm².
A circle has radius 43 cm. Its area is kπ cm². Find k.
A circle has radius 73 cm. Its circumference is kπ cm. Find k.
Answer key
- 80.5 cm² (20 + 3) × 7 ÷ 2 = 80.5
- 567 cm² 7 × 9² = 567
- 2601 A = π × 51² = 2601π → k = 2601
- 142 C = 2 × π × 71 = 142π
- 288 cm² (30 + 2) × 18 ÷ 2 = 288
- 216 cm² 24 × 3² = 216
- 4096 A = π × 64² = 4096π → k = 4096
- 50 C = 2 × π × 25 = 50π
- 210 cm² (17 + 13) × 14 ÷ 2 = 210
- 1274 cm² 26 × 7² = 1274
- 1849 A = π × 43² = 1849π → k = 1849
- 146 C = 2 × π × 73 = 146π
Review worksheet: 12 questions
A trapezoid has parallel sides 30 cm and 23 cm and height 7 cm. Find its area in cm².
A shape has area 16 cm². All lengths are multiplied by 6. Find the new area in cm².
A circle has radius 42 cm. Its area is kπ cm². Find k.
A circle has radius 51 cm. Its circumference is kπ cm. Find k.
A trapezoid has parallel sides 28 cm and 9 cm and height 19 cm. Find its area in cm².
A shape has area 51 cm². All lengths are multiplied by 4. Find the new area in cm².
A circle has radius 47 cm. Its area is kπ cm². Find k.
A circle has radius 63 cm. Its circumference is kπ cm. Find k.
A trapezoid has parallel sides 26 cm and 17 cm and height 18 cm. Find its area in cm².
A shape has area 43 cm². All lengths are multiplied by 6. Find the new area in cm².
A circle has radius 69 cm. Its area is kπ cm². Find k.
A circle has radius 50 cm. Its circumference is kπ cm. Find k.
Answer key
- 185.5 cm² (30 + 23) × 7 ÷ 2 = 185.5
- 576 cm² 16 × 6² = 576
- 1764 A = π × 42² = 1764π → k = 1764
- 102 C = 2 × π × 51 = 102π
- 351.5 cm² (28 + 9) × 19 ÷ 2 = 351.5
- 816 cm² 51 × 4² = 816
- 2209 A = π × 47² = 2209π → k = 2209
- 126 C = 2 × π × 63 = 126π
- 387 cm² (26 + 17) × 18 ÷ 2 = 387
- 1548 cm² 43 × 6² = 1548
- 4761 A = π × 69² = 4761π → k = 4761
- 100 C = 2 × π × 50 = 100π
7.SP Statistics and Probability
Statistics & probability
Simple probability, probability of an event not happening and probability of two events.
Short lesson: Two draws with replacement
Study guide for Grades 7 to 10: 2 worked examples and 2 practice questions. Replacing the first item keeps the second probability unchanged.
P(A then A) = P(A)²; independent draws
Replacing the first item keeps the second probability unchanged.
Worked example
A bag has 5 red and 6 blue counters. Draw twice, replacing the first counter. What is the probability both are red? Give a simplified fraction.
5/11 × 5/11 = 25/121
Answer: 25/121
Worksheets
A practice worksheet and a review worksheet, 12 and 12 questions.
Practice worksheet: 12 questions
A bag has 8 red and 10 blue counters. Draw twice, replacing the first counter. What is the probability both are red? Give a simplified fraction.
P(A) = 13/36. Find P(not A).
A bag contains 7 red counters and 27 blue counters. One counter is drawn at random. What is the probability of red?
A bag has 10 red and 14 blue counters. Draw twice, replacing the first counter. What is the probability both are red? Give a simplified fraction.
P(A) = 2/6. Find P(not A).
A bag contains 3 red counters and 13 blue counters. One counter is drawn at random. What is the probability of red?
A bag has 8 red and 15 blue counters. Draw twice, replacing the first counter. What is the probability both are red? Give a simplified fraction.
P(A) = 13/33. Find P(not A).
A bag contains 29 red counters and 28 blue counters. One counter is drawn at random. What is the probability of red?
A bag has 8 red and 4 blue counters. Draw twice, replacing the first counter. What is the probability both are red? Give a simplified fraction.
P(A) = 26/29. Find P(not A).
A bag contains 18 red counters and 14 blue counters. One counter is drawn at random. What is the probability of red?
Answer key
- 16/81 8/18 × 8/18 = 16/81
- 23/36 1 − 13/36 = 23/36
- 7/34 7/(7 + 27) = 7/34
- 25/144 10/24 × 10/24 = 25/144
- 2/3 1 − 2/6 = 2/3
- 3/16 3/(3 + 13) = 3/16
- 64/529 8/23 × 8/23 = 64/529
- 20/33 1 − 13/33 = 20/33
- 29/57 29/(29 + 28) = 29/57
- 4/9 8/12 × 8/12 = 4/9
- 3/29 1 − 26/29 = 3/29
- 9/16 18/(18 + 14) = 9/16
Review worksheet: 12 questions
P(A) = 7/20. Find P(not A).
A bag has 10 red and 1 blue counters. Draw twice, replacing the first counter. What is the probability both are red? Give a simplified fraction.
A bag contains 8 red counters and 35 blue counters. One counter is drawn at random. What is the probability of red?
P(A) = 10/15. Find P(not A).
A bag has 2 red and 1 blue counters. Draw twice, replacing the first counter. What is the probability both are red? Give a simplified fraction.
A bag contains 5 red counters and 11 blue counters. One counter is drawn at random. What is the probability of red?
P(A) = 23/25. Find P(not A).
A bag has 10 red and 2 blue counters. Draw twice, replacing the first counter. What is the probability both are red? Give a simplified fraction.
A bag contains 16 red counters and 8 blue counters. One counter is drawn at random. What is the probability of red?
P(A) = 17/32. Find P(not A).
A bag has 11 red and 15 blue counters. Draw twice, replacing the first counter. What is the probability both are red? Give a simplified fraction.
A bag contains 16 red counters and 20 blue counters. One counter is drawn at random. What is the probability of red?
Answer key
- 13/20 1 − 7/20 = 13/20
- 100/121 10/11 × 10/11 = 100/121
- 8/43 8/(8 + 35) = 8/43
- 1/3 1 − 10/15 = 1/3
- 4/9 2/3 × 2/3 = 4/9
- 5/16 5/(5 + 11) = 5/16
- 2/25 1 − 23/25 = 2/25
- 25/36 10/12 × 10/12 = 25/36
- 2/3 16/(16 + 8) = 2/3
- 15/32 1 − 17/32 = 15/32
- 121/676 11/26 × 11/26 = 121/676
- 4/9 16/(16 + 20) = 4/9