Question

The radii of two spheres are in ratio 1 : 2. Find the ratio of their surface areas.

Answer 1

$r_1$ = 1

$r_2$ =2
area of two surfaces of sphere = $\frac{\frac{4}{3}\pi r_1^2}{\frac{4}{3}\pi r_2^2}$
= $\frac{r_1^2}{r_2^2}$
=${\frac{1}{2}}^2$
=$\frac{1}{4}$