<PRE><B>Question 1093873</B>
The intensity of light (in foot-candle) varies inversely as the square of the distance (in feet) from the light source. The intensity of light 3 feet from the source is 72 foot-candles. How far away is the source if the intensity of light is 2 foot-candles
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The intensity of light (in foot-candle) varies inversely as the square of the distance (in feet) from the light source. The intensity of light 3 feet from the source is 72 foot-candles. How far away is the source if the intensity of light is 2 foot-candles
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I = k/d^2 where k is a constant.
72 = k/3^2
k = 72*9 = 648
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How far away is the source if the intensity of light is 2 foot-candles
2 = 648/d^2
d^2 = 648/2 = 324
d = 18 ft</PRE>