South Korea · Grade 7 · Practice Sheet 23

1. 1.

   A value changes from 177 to 44. Find the percentage change (to 2 d.p.).

   Formula:Percentage Change

   $\%\,\text{change} = \dfrac{\text{new} - \text{old}}{\text{old}} \times 100$

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2. 2.

   What is 25% of 240?

   Formula:Percentage of a Quantity

   $\text{result} = \dfrac{p}{100} \times N$

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3. 3.

   Find the perimeter of a rectangle measuring 15 m by 21 m.

   Formula:Perimeter of a Rectangle

   $P = 2(l + w)$

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4. 4.

   A bag has 17 equally likely marbles, of which 2 are red. Find the probability of drawing a red marble (to 3 d.p.).

   Formula:Simple Probability

   $P(E) = \dfrac{\text{favourable}}{\text{total}}$

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5. 5.

   A value changes from 45 to 211. Find the percentage change (to 2 d.p.).

   Formula:Percentage Change

   $\%\,\text{change} = \dfrac{\text{new} - \text{old}}{\text{old}} \times 100$

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6. 6.

   ₩5,000 is invested at 7.5% simple interest per year for 3 years. Find the interest earned.

   Formula:Simple Interest

   $I = \dfrac{P \times r \times t}{100}$

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7. 7.

   Find the mean (average) of these numbers: 56, 69, 86, 75, 44, 91.

   Formula:Arithmetic Mean

   $\bar{x} = \dfrac{\sum x}{n}$

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8. 8.

   A circle has a radius of 9 cm. Find its area. (Use π ≈ 3.14159)

   Formula:Area of a Circle

   $A = \pi r^2$

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9. 9.

   Find the perimeter of a rectangle measuring 19 m by 31 m.

   Formula:Perimeter of a Rectangle

   $P = 2(l + w)$

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10. 10.

    ₩4,200 is invested at 3% simple interest per year for 5 years. Find the interest earned.

    Formula:Simple Interest

    $I = \dfrac{P \times r \times t}{100}$

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11. 11.

    Find the perimeter of a rectangle measuring 6 m by 4 m.

    Formula:Perimeter of a Rectangle

    $P = 2(l + w)$

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12. 12.

    Find the mean (average) of these numbers: 75, 48, 40, 38, 35, 89.

    Formula:Arithmetic Mean

    $\bar{x} = \dfrac{\sum x}{n}$

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13. 13.

    A rectangle is 8 cm long and 3 cm wide. Find its area.

    Formula:Area of a Rectangle

    $A = l \times w$

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14. 14.

    Find the perimeter of a rectangle measuring 42 m by 25 m.

    Formula:Perimeter of a Rectangle

    $P = 2(l + w)$

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15. 15.

    A train moves at 86 km/h for 3.1 hours. How far does it travel?

    Formula:Distance from Speed & Time

    $d = v \times t$

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16. 16.

    Find the circumference of a circle whose radius is 12 m. (Use π ≈ 3.14159)

    Formula:Circumference of a Circle

    $C = 2\pi r$

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17. 17.

    Solve for x: 4x + 10 = 22.

    Formula:Solving a Linear Equation

    $x = \dfrac{c - b}{a}$

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18. 18.

    A value changes from 122 to 185. Find the percentage change (to 2 d.p.).

    Formula:Percentage Change

    $\%\,\text{change} = \dfrac{\text{new} - \text{old}}{\text{old}} \times 100$

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19. 19.

    A bag has 28 equally likely marbles, of which 21 are red. Find the probability of drawing a red marble (to 3 d.p.).

    Formula:Simple Probability

    $P(E) = \dfrac{\text{favourable}}{\text{total}}$

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20. 20.

    A triangle has a base of 32 cm and a height of 22 cm. Find its area.

    Formula:Area of a Triangle

    $A = \tfrac{1}{2} b h$

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