If the distance between a point source of light and a screen is doubled, then the intensity will be

 if the distance between a point source of light and a screen is doubled, then the intensity will be one fourth

Solution

Intensity, I ∝ 1/d2

Where d = distance between the source and surface.

So if the distance between the source and surface is doubled i.e. d’ = 2d, then the intensity of light falling on the surface becomes one fourth

 I’ = 1/(2d)2 = (¼)I