Radius of a sphere and edge of a cube are equal ratio of their surface area is

Radius of sphere $=$ Edge of a cube

$r=a$

$\frac{\text{S}\text{.A of sphere}}{\text{S}\text{.A of cube}}=\frac{4\pi r^2}{6a^2}$

$=\frac{4\pi r^2}{6r^2}$

$=\frac{4\pi }{6}$ of $\frac{2\pi }{3}$

$=\frac{4\times 22}{6\times 7}$

$=\frac{44}{21}$

$\therefore$ S.A of sphere $:$ S.A of cube $=2\pi :3$