Question

The radius of a cylinder is increased by 15% and its height is decreased by 20%. Find the percentage change in the volume of the cylinder.

Answer 1

first cylinder(V1) =
`\pi`r²h

insert 10 as r&h
⇒V1 = 1000
`\pi`

second cylinder(V2)=
`\pi` ×11.5² × 8 = 1058
`\pi`

V2-V1 = 58
`\pi`

100 ×
`(58 \pi )/(1000 \pi )` = 5.8% increase