Surround Ground

Electricity and Magnetism Level 3

A $1~\mbox{nC}$ charge is placed inside a grounded conducting hollow sphere of radius $10~\mbox{cm}$ centered on the origin. If the charge is placed at $(5~\mbox{cm},0,0)$ , what is the electric potential at $(-5~\mbox{cm},0,0)$ ?

Details and assumptions

Let $1/4 \pi \epsilon_0=K=9\times 10^9 ~\mbox{Nm}^2/\mbox{C}^2$ .