SOLUTION: Please help, can't seem to find a solution: The intensity of light (in foot-candle) varies inversely as the square of the distance (in feet) from the light source. The intensity o

Algebra.Com
Question 1093873: Please help, can't seem to find a solution:
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
Thanks!

Answer by Alan3354(69443)   (Show Source): You can put this solution on YOUR website!
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
----------
What have you tried?
=========================
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
----
I = k/d^2 where k is a constant.
72 = k/3^2
k = 72*9 = 648
============
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

RELATED QUESTIONS

Please Help: The intensity of light (in foot-candle) varies inversely as the square of... (answered by ankor@dixie-net.com)
Hello can I please get help for these 3 problems: Problem 1: The score S on a Math 012... (answered by ikleyn)
the intensity of light, l, received at a source varies inversely as the square of the the (answered by DrBeeee)
The intensity of light received from a source varies inversely as the square of the... (answered by Fombitz)
The intensity 1, of light received from a source varies inversely as the square of the... (answered by josgarithmetic)
The illumination (in foot-candles) of a light source varies directly as the intensity... (answered by stanbon)
the intensity I of light varies inversely as the square of the distance D from the source (answered by rothauserc,greenestamps)
The intensity of light received at a source varies inversely as the square of the... (answered by solver91311)
The intensity I of light varies inversely as the sqaure of the distance D from the... (answered by ankor@dixie-net.com)