Czechia · Grade 7 · Practice Sheet 17

1. 1.

   Find the mean (average) of these numbers: 16, 20, 30, 78, 41, 47.

   Formula:Arithmetic Mean

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

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2. 2.

   Solve for x: 2x + 11 = 21.

   Formula:Solving a Linear Equation

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

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3. 3.

   Convert 5.11 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 18 cm and 9 cm. Find the length of the hypotenuse.

   Formula:Pythagorean Theorem

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

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5. 5.

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

   Formula:Area of a Square

   $A = s^2$

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6. 6.

   Find the circumference of a circle whose radius is 14 m. (Use π ≈ 3.14159)

   Formula:Circumference of a Circle

   $C = 2\pi r$

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7. 7.

   A circle has a radius of 5 cm. Find its area. (Use π ≈ 3.14159)

   Formula:Area of a Circle

   $A = \pi r^2$

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8. 8.

   A bag has 30 equally likely marbles, of which 5 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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9. 9.

   Find the area of a square with side length 30 cm.

   Formula:Area of a Square

   $A = s^2$

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10. 10.

    Kč 108 is shared in the ratio 1 : 2. Find each share.

    Formula:Dividing in a Ratio

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

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11. 11.

    Find the area of a square with side length 23 cm.

    Formula:Area of a Square

    $A = s^2$

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12. 12.

    A circle has a radius of 21 cm. Find its area. (Use π ≈ 3.14159)

    Formula:Area of a Circle

    $A = \pi r^2$

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13. 13.

    One item costs Kč 16.61. Find the total cost of 17 items.

    Formula:Total Cost

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

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14. 14.

    Find the area of a square with side length 8 cm.

    Formula:Area of a Square

    $A = s^2$

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15. 15.

    Kč 2,200 is invested at 8% simple interest per year for 6 years. Find the interest earned.

    Formula:Simple Interest

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

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16. 16.

    A value changes from 168 to 184. 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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17. 17.

    One item costs Kč 23.83. Find the total cost of 20 items.

    Formula:Total Cost

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

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18. 18.

    Find the area of a square with side length 12 cm.

    Formula:Area of a Square

    $A = s^2$

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19. 19.

    One item costs Kč 12.89. Find the total cost of 19 items.

    Formula:Total Cost

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

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20. 20.

    Find 6/8 of 88.

    Formula:Fraction of a Quantity

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

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