WAEC - Mathematics (2014 - No. 37)
The radii of the base of two cylindrical tins, P and Q are r and 2r respectively. If the water level in p is 10cm high, what would be the height of the same quantity of water in Q?
2.5cm
5.0cm
7.5cm
20.0cm
Explanation
volume of cylinder = \(\pi r^2h\)
volume of cylinder p = \(\pi r^2 \times 10\)
= 10\(\pi r^2\)
volume of cylinder Q = \(\pi (2r)^2 h\)
= 4\(\pi r^2\)h
4\(\pi r^2h = 10 \pi r^2\)
h = \(\frac{10}{4} = 2.5cm\)
volume of cylinder p = \(\pi r^2 \times 10\)
= 10\(\pi r^2\)
volume of cylinder Q = \(\pi (2r)^2 h\)
= 4\(\pi r^2\)h
4\(\pi r^2h = 10 \pi r^2\)
h = \(\frac{10}{4} = 2.5cm\)
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