Given the electric flux density, D $=0\mathrm{.}3$r$2$ar nC$/$m$2$ in free space: $($a$)$ find E at point P$($r $=2,$ $=25,=90)$; $($b$)$ find the total charge within the sphere r $=3$; $($c$)$ find the total electric flux leaving the sphere r $=4.$

Ans. $($a$)135\mathrm{.}5$ar V$/$m; $($b$)305$ nC; $($c$)965$ nC

Ans. $($a$)6\mathrm{.}38$ax $9\mathrm{.}57$ay $+19\mathrm{.}14$az $$C$/$m$2$; $($b$)212$ay $+424$az $$C$/$m$2$; $($c$)60$az $$C$/$m$2$