Sri Lanka · Grade 7 · Practice Sheet 24

1. 1.

   Find the circumference of a circle whose radius is 17 m. (Use π ≈ 3.14159)

   Formula:Circumference of a Circle

   $C = 2\pi r$

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2. 2.

   A bag has 17 equally likely marbles, of which 11 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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3. 3.

   Convert 11.06 kilometres into metres.

   Formula:Metric Length Conversion

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

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4. 4.

   A right-angled triangle has legs of 8 cm and 20 cm. Find the length of the hypotenuse.

   Formula:Pythagorean Theorem

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

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5. 5.

   A value changes from 69 to 97. 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.

   Find the mean (average) of these numbers: 32, 73, 29, 70, 42.

   Formula:Arithmetic Mean

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

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7. 7.

   A rectangle is 25 cm long and 3 cm wide. Find its area.

   Formula:Area of a Rectangle

   $A = l \times w$

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8. 8.

   Find the perimeter of a rectangle measuring 21 m by 34 m.

   Formula:Perimeter of a Rectangle

   $P = 2(l + w)$

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9. 9.

   Find 3/4 of 80.

   Formula:Fraction of a Quantity

   $\text{result} = \dfrac{a}{b} \times N$

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10. 10.

    Find the area of a square with side length 17 cm.

    Formula:Area of a Square

    $A = s^2$

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11. 11.

    A value changes from 173 to 129. 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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12. 12.

    Find the mean (average) of these numbers: 17, 80, 48, 80, 68.

    Formula:Arithmetic Mean

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

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13. 13.

    Rs 4,300 is invested at 7.5% simple interest per year for 4 years. Find the interest earned.

    Formula:Simple Interest

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

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14. 14.

    Solve for x: 6x + 11 = 53.

    Formula:Solving a Linear Equation

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

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15. 15.

    A car travels 623 km in 7 hours. Find its average speed.

    Formula:Speed

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

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16. 16.

    Find the mean (average) of these numbers: 15, 41, 29, 45, 49.

    Formula:Arithmetic Mean

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

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17. 17.

    Find the circumference of a circle whose radius is 16 m. (Use π ≈ 3.14159)

    Formula:Circumference of a Circle

    $C = 2\pi r$

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18. 18.

    Find 1/2 of 16.

    Formula:Fraction of a Quantity

    $\text{result} = \dfrac{a}{b} \times N$

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19. 19.

    A rectangle is 25 cm long and 23 cm wide. Find its area.

    Formula:Area of a Rectangle

    $A = l \times w$

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20. 20.

    A bag has 29 equally likely marbles, of which 17 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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