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WAEC Mathematics 2022 Paper

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Question : 37

Total: 47

Find the correct to two decimal places, the volume of a sphere whose radius is 3cm. [Take π =

\frac{22}{7}

]

72.57cm $^3$
88.12cm $^3$
10529cm $^3$
113.14cm $^3$

Solution:

Concept:

The volume of a sphere is found using the formula

V = \frac{4}{3}\pi r^3

.

Explanation:

Given radius

r = 3

cm and

\pi = \frac{22}{7}

.

Substitute into the formula:

V = \frac{4}{3} \times \frac{22}{7} \times (3)^3

.

This gives

V = \frac{4}{3} \times \frac{22}{7} \times 27

.

Cancel the common factor 3:

V = 4 \times \frac{22}{7} \times 9

.

So

V = \frac{792}{7} = 113.142857...

.

Correct to two decimal places:

V = 113.14\,\text{cm}^3

.

Answer:

113.14\,\text{cm}^3

(Option D).

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