[tex]\bf \begin{array}{llll}
\textit{surface area of a sphere}\\\\
s=4\pi r^2
\\\\\\
\textit{volume of a sphere}\\\\
V=\cfrac{4\pi r^3}{3}
\end{array}\quad
\begin{cases}
r=radius\\
-----\\
r=3960
\end{cases}
\\\\\\\\
\cfrac{s}{V}\qquad \cfrac{4\pi 3960^2}{\frac{4\pi 3960^3}{3}}\implies \cfrac{\frac{4\pi 3960^2}{1}}{\frac{4\pi 3960^3}{3}}\implies \cfrac{4\pi 3960^2}{1}\cdot \cfrac{3}{4\pi 3960^3}
\\\\\\
\cfrac{3}{3960}\implies \cfrac{1}{1320}[/tex]
