Sphere with density proportional to the radius

An insulating sphere of radius $R=5.0\mathrm{cm}$ is charged with density $\rho (r)={\rho }_0\frac{r}{R}$, with ${\rho }_0=4.0\mu C/{\mathrm{m}}^3$. Compute the total charge, the field inside as a function of $r$ and its magnitude at the surface.