Let $ρ(r)=\frac{Q}{\pi R^4}$ be the charge density distribution for a solid non-conducting sphere of radius R and total charge Q. For a point P inside the sphere at distance r, from the centre of the sphere, the magnitude of electric field is

$\frac{Qr_1^2}{4πε_0R^4}$

$\text{Consider a differential thickness dr at a radius r.}$

$\text{We get the volume for this differential thickness as } dV = 4\pi r^2 dr$

$\Rightarrow E.4\pi r_1^2 = \frac{Q}{\epsilon_0} = \frac{Qr_1^4}{\epsilon_0 R^4}$

$\Rightarrow E = \frac{Qr_1^2}{4\pi\epsilon_0 R^4}$