WAEC 2024 · Paper 1 · Q14

Solid mensuration

A cylindrical metallic barrel of height $2.5\text{ m}$ and radius $0.245\text{ m}$ is closed at one end. Find, correct to one decimal place, the total surface area of the barrel. $\left[\text{Take }\pi = \frac{22}{7}\right]$

Worked solution (try it first)

Closed at one end: the curved surface plus one circle, $2\pi rh + \pi r^2$ .
Curved surface: $2 \times \frac{22}{7} \times 0.245 \times 2.5 = 3.85\text{ m}^2$ .
One end: $\frac{22}{7} \times 0.245^2 \approx 0.19\text{ m}^2$ .
Total: $3.85 + 0.19 = 4.04$ , which is $4.0\text{ m}^2$ to 1 decimal place, option C.

Report a problem with this question