JAMB - Mathematics (2021 - No. 20)
A cylinder pipe, made of metal is 3cm thick.If the internal radius of the pipe is 10cm.Find the volume of metal used in making 3m of the pipe.
153\(\pi\)cm3
207\(\pi\)cm3
15 300\(\pi\)cm3
20 700\(\pi\)cm3
解释
Volume of a cylinder = πr\(^2\)h
First convert 3m to cm by multiplying by 100
Volume of External cylinder = \(π \times 13^2 \times 300\)
Volume of Internal cylinder = \(π \times 10^2 \times 300\)
Hence; Volume of External cylinder - Volume of Internal cylinder
Total volume (v) = \(π (169 - 100) \times 300\)
V = \(π \times 69 \times 300\)
V = 20700πcm\(^3\)