Question

If the radius of a sphere is double, what will be the ratio of its total surface area to that of first sphere.

Answer 1

Total surface area of sphere = $4\pi {r}^{2}$

TSA when radius is doubled = $4\pi(2r) {}^{2} = 16\pi {r}^{2}$

Ratio = $\frac{16\pi {r}^{2} }{4\pi {r}^{2} } = \frac{4}{1}$ = 1:4