Solve
-The Intensity I of Light Varies Inversely as the Square

Multiple Choice

Solve.
-The intensity I of light varies inversely as the square of the distance D from the source. If the intensity of illumination on a screen 5 ft from a light is 4 foot candles, find the intensity on a screen 20 ft from the light.
Express the answer as a fraction.

A) 4 foot-candles
B) $\frac { 1 } { 5 }$ foot-candle
C) $\frac { 1 } { 4 }$ foot-candle
D) 2 foot-candles