Question

Radius of solid right circular cylinder decrease by 20% & its height increase by 10% find %change in its volume

Answer 1

let radius=r,height=h
new radius=.80r,new height=1.1h
old vol of cyl.=pi*r^2*h
new vol=pi*(.8r)^2*(1.1h)
=.704pi*r^2*h
% reduction=.269*100=26.9%