JAMB 2016 · UTME · Q23

Solid mensuration

A cylindrical pipe $50\text{ m}$ long with radius $7\text{ m}$ has one end open. What is the total surface area of the pipe?

Worked solution (try it first)

One end open means one end is closed: the curved surface plus one circle.
Curved surface: $2\pi rh = 2\pi \times 7 \times 50$
$= 700\pi$ .
One end: $\pi r^2 = 49\pi$ .
Total: $700\pi + 49\pi = 749\pi\text{ m}^2$ , option D.

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