Question

The intensity of I of light from a light bulb, measured in watts per square meter (w/m^2), varies inversely as the square of the distance d from the light bulb. Suppose I is 85 w/m^2 when the distance is 5m. Find the intensity when the distance from the light bulb is 2m away.

Answer 1

I= ___ w/m^2
(simplify your answer. Type an integer,fraction, or mixed number.)

Answer 2

since I = k/d^2, I*d^2 = k, a constant. So, just set it up:

85*5^2 = I*2^2

Now just solve for I.