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 × $\frac{58 \pi }{1000 \pi }$ = 5.8% increase