Answer
% error in circumference is 2%
% error in area is 4%
Work Step by Step
The given % error change in radius is: $\frac{dr}{r}$ = 0.02
since % error change = $\frac{change\ in\ dimension}{original\ dimension}$
$C=2\pi r$
$dC=2\pi dr$
$A=\pi r^2$
$dA=2\pi r dr$
% error in circumference = $\frac{dC}{c}=\frac{2\pi dr}{2\pi r}=0.02$
% error in area = $\frac{dA}{A}=\frac{\pi 2r\times dr}{\pi r^2}=0.04$
