Write a power function for the following situation, and then use the equation to solve for the missing information. 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 feet from a light is 2 foot-candles, find the intensity of illumination on a screen 5 feet from the light.
Did you ask the correct queston???...we aleady know the intensity 5 feet from the light....
Here's the equation we need
I = k / D^2 ..... and we need to find the proportionality constant, "k"....
So we have....
2 = k / 5^2
2 = k / 25 multiply both sides by 25
50 = k
And we need to solve this
I = 50 / 15^2
I = 50 / 225
I = 10 / 45 = 2 / 9 foot-candles