A hollow charged metal sphere has a radius R. If the potential difference between its surface and a point distant 3R from it center is V, then the electric field at a distance 3R from its center is

$\frac{V}{6R}$

$ V = \frac{kQ}{R} - \frac{kQ}{3R} = \frac{2kQ}{3R}$

$ \text{Electric Field at 3R is } E = \frac{kQ}{9R^2} = \frac{V}{6R}$