WAEC 2023 · Paper 1 · Q23

Solid mensuration

An empty cylindrical tank is $140\text{ cm}$ in diameter. If 200 litres of water are poured into the tank, calculate, correct to the nearest centimetre, the height of the water in the tank. $\left[\text{Take }\pi = \frac{22}{7}\right]$

Worked solution (try it first)

Change litres to cm³: 200 litres is $200\,000\text{ cm}^3$ .
The radius is $140 \div 2 = 70$ cm.
Base area: $\frac{22}{7} \times 70^2 = 15\,400\text{ cm}^2$ .
Height $= 200\,000 \div 15\,400 \approx 12.99$ , which is 13 cm to the nearest centimetre, option C.

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