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WAEC Mathematics 2012 Paper

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Question : 14

Total: 49

The curved surface area of a cylindrical tin is 704cm². If the radius of its base is 8cm, find the height. [Take

\pi = \; \frac{22}{7}

]`

14cm
9cm
8cm
7cm

Solution:

Concept:

The curved surface area of a cylinder is

2\pi r h

.

Explanation:

Given: curved surface area

= 704\text{ cm}^2

and base radius

r = 8\text{ cm}

.

Substitute into the formula:

2\pi r h = 704

.

2 \times \frac{22}{7} \times 8 \times h = 704

\frac{352}{7}h = 704

Multiply both sides by

7

:

352h = 704 \times 7

352h = 4928

h = \frac{4928}{352}

h = 14\text{ cm}

.

Answer:

The height of the cylinder is

14\text{ cm}

, which is option A.

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