Electric potential at a point '$\mathrm{P}$' due to a point charge of $5 \times 10^{-9} \mathrm{C}$ is $50 \mathrm{~V}$. The distance of '$\mathrm{P}$' from the point charge is:

(Assume, $\frac{1}{4 \pi \varepsilon_{0}}=9 \times 10^{+9} ~\mathrm{Nm}^{2} \mathrm{C}^{-2}$ )