JAMB 1998 · UME · Q6

Solid mensuration
Commercial arithmetic

A market woman sells oil in cylindrical tins 10 cm deep and 6 cm in diameter at ₦15.00 each. If she bought a full cylindrical jug 18 cm deep and 10 cm in diameter for ₦50.00, how much did she make by selling all the oil?

Worked solution (try it first)

Tin: radius 3 cm, so its volume is $\pi \times 3^2 \times 10 = 90\pi\text{ cm}^3$ .
Jug: radius 5 cm, so its volume is $\pi \times 5^2 \times 18 = 450\pi\text{ cm}^3$ .
That fills $450\pi \div 90\pi = 5$ tins.
She takes in $5 \times 15 = 75$ naira.
Profit: $75 - 50 = 25$ , so ₦25.00, option D.

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