Germany · Klasse 7 · Practice Sheet 21

1. 1.

   €5,000 is invested at 8% 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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2. 2.

   Find the perimeter of a rectangle measuring 32 m by 31 m.

   Formula:Perimeter of a Rectangle

   $P = 2(l + w)$

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3. 3.

   A triangle has a base of 4 cm and a height of 25 cm. Find its area.

   Formula:Area of a Triangle

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

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4. 4.

   A value changes from 160 to 149. 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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5. 5.

   €320 is shared in the ratio 3 : 5. Find each share.

   Formula:Dividing in a Ratio

   $\text{share} = \dfrac{\text{part}}{\text{total parts}} \times T$

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6. 6.

   Find the mean (average) of these numbers: 93, 16, 40, 60, 12, 13.

   Formula:Arithmetic Mean

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

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7. 7.

   Find the perimeter of a rectangle measuring 39 m by 32 m.

   Formula:Perimeter of a Rectangle

   $P = 2(l + w)$

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8. 8.

   One item costs €22.2. Find the total cost of 10 items.

   Formula:Total Cost

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

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9. 9.

   €4,100 is invested at 7.5% simple interest per year for 2 years. Find the interest earned.

   Formula:Simple Interest

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

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10. 10.

    Find the mean (average) of these numbers: 46, 66, 21, 18, 38.

    Formula:Arithmetic Mean

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

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11. 11.

    Solve for x: 8x + 10 = 58.

    Formula:Solving a Linear Equation

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

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12. 12.

    A bag has 19 equally likely marbles, of which 7 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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13. 13.

    A right-angled triangle has legs of 12 cm and 18 cm. Find the length of the hypotenuse.

    Formula:Pythagorean Theorem

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

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14. 14.

    Find the perimeter of a rectangle measuring 24 m by 30 m.

    Formula:Perimeter of a Rectangle

    $P = 2(l + w)$

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15. 15.

    Solve for x: 6x + 7 = 31.

    Formula:Solving a Linear Equation

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

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16. 16.

    Convert 3.89 kilometres into metres.

    Formula:Metric Length Conversion

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

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17. 17.

    Find the mean (average) of these numbers: 75, 61, 34, 30.

    Formula:Arithmetic Mean

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

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18. 18.

    What is 10% of 360?

    Formula:Percentage of a Quantity

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

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19. 19.

    Find 1/3 of 36.

    Formula:Fraction of a Quantity

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

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20. 20.

    Find the perimeter of a rectangle measuring 20 m by 31 m.

    Formula:Perimeter of a Rectangle

    $P = 2(l + w)$

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