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WAEC Mathematics 2022 Paper

Question : 23

Total: 47

Solution:

Concept:

An open-ended cylinder has only one circular base, so its surface area is the sum of the base area and the curved surface area.

Explanation:

Total surface area of an open-top cylinder is given by:

\pi r^2 + 2\pi r h = \pi r(r + 2h)

Here, radius

r = 3.5\text{ cm}

and height

h = 8\text{ cm}

Take

\pi = \frac{22}{7}

Substitute the values:

\text{Total surface area} = \frac{22}{7} \times 3.5 \times (3.5 + 2 \times 8)

Simplify inside the bracket:

3.5 + 16 = 19.5

So:

\frac{22}{7} \times 3.5 \times 19.5 = 11 \times 19.5 = 214.5\text{ cm}^2

Answer:

The total surface area is

214.5\text{ cm}^2

, which is Option D.

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