South Korea · Grade 7 · Practice Sheet 8

1. 1.

   Find the mean (average) of these numbers: 77, 52, 59, 67, 30.

   Formula:Arithmetic Mean

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

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2. 2.

   A car travels 560 km in 7 hours. Find its average speed.

   Formula:Speed

   $v = \dfrac{d}{t}$

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3. 3.

   A train moves at 22 km/h for 4.7 hours. How far does it travel?

   Formula:Distance from Speed & Time

   $d = v \times t$

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4. 4.

   One item costs ₩18.84. Find the total cost of 15 items.

   Formula:Total Cost

   $\text{total} = \text{price} \times \text{quantity}$

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5. 5.

   A right-angled triangle has legs of 20 cm and 7 cm. Find the length of the hypotenuse.

   Formula:Pythagorean Theorem

   $c = \sqrt{a^2 + b^2}$

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6. 6.

   A value changes from 48 to 92. 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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7. 7.

   One item costs ₩13.51. Find the total cost of 9 items.

   Formula:Total Cost

   $\text{total} = \text{price} \times \text{quantity}$

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8. 8.

   A rectangle is 32 cm long and 29 cm wide. Find its area.

   Formula:Area of a Rectangle

   $A = l \times w$

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9. 9.

   Solve for x: 6x + 15 = 87.

   Formula:Solving a Linear Equation

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

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10. 10.

    ₩3,400 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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11. 11.

    A train moves at 54 km/h for 4.2 hours. How far does it travel?

    Formula:Distance from Speed & Time

    $d = v \times t$

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12. 12.

    A car travels 260 km in 4 hours. Find its average speed.

    Formula:Speed

    $v = \dfrac{d}{t}$

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13. 13.

    A bag has 27 equally likely marbles, of which 24 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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14. 14.

    Convert 6.01 kilometres into metres.

    Formula:Metric Length Conversion

    $1\,\text{km} = 1000\,\text{m}$

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15. 15.

    Find the mean (average) of these numbers: 25, 89, 67, 78.

    Formula:Arithmetic Mean

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

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16. 16.

    A bag has 10 equally likely marbles, of which 6 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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17. 17.

    Solve for x: 3x + 12 = 18.

    Formula:Solving a Linear Equation

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

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18. 18.

    A rectangle is 30 cm long and 14 cm wide. Find its area.

    Formula:Area of a Rectangle

    $A = l \times w$

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19. 19.

    Find the perimeter of a rectangle measuring 17 m by 33 m.

    Formula:Perimeter of a Rectangle

    $P = 2(l + w)$

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20. 20.

    A car travels 188 km in 2 hours. Find its average speed.

    Formula:Speed

    $v = \dfrac{d}{t}$

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