Charge is distributed within a sphere of radius R with a volume charge density ρ( r )=A/(r^2) e^-2 r / a, where A and a are constants. If Q is the…

Charge is distributed within a sphere of radius $\displaystyle R$ with a volume charge density $\displaystyle \rho(\mathrm{r})=\frac{\mathrm{A}}{\mathrm{r}^2} \mathrm{e}^{-2 \mathrm{r} / \mathrm{a}}$, where A and a are constants. If Q is the total charge of this charge distribution, the radius R is :