Question

The ratio of the volume of the sphere to the surface area of the sphere is 7 : 1. Find the surface area of the sphere ?

Answer 1

Volume of sphere = $\frac{4}{3}\pi r^3$

Surface area of sphere = $4\pi r^2$

Given that,

$\frac{\frac{4}{3}\pi r^3}{4\pi r^2}=7$

$\frac{1}{3}r=7$

$r=21$

Therefore, surface area = $4\times \frac{22}{7}\times {21}^2=5544$ sq. unit