For a light that has an intensity of 60 candles at its source, the intensity in candles, S, of the light at a point d d feet from the source is given by the formula S=60k/d^2 60, where k is a constant. If the intensity of the light is 20 candles at a distance of 3 feet from the source, what is the intensity of the light at a distance of 30 feet from the source?
Choose the correct choice from the following answers.
A) 3/10 candles
B) 1/2 candles
C) 1 1/3 candles
D) 1/5 candles
E) 3 candles
ANS = 3/10   S= 60k/d^2   At 3 feet   20 = 60k/9 so k = 3   At 20 feet   S = 60 *3/30^2 = 1/5   1/5 candles
<result>D</result>
For a light that has an intensity of 60 candles at its source, the intensity in candles, S, of the light at a point d d feet from the source is given by the formula S=60k/d^2 60, where k is a constant. If the intensity of the light is 20 candles at a distance of 3 feet from the source, what is the intensity of the light at a distance of 30 feet from the source?