The Intensity I of light from a light bulb varies inversley as the square of the distance d from the light bulb.
Creating a formula from this information gives us,
I = k/d^2, where k is a constant of proportionality.
I is 360 w/m (squared) when the distance is 3 m. From this we can write,
360 = k/3^2
Therefore k = 360*9 = 3,240.
How much farther would it be to a point where the Intensity is 250 w/m(squared)?
When I = 250 w/m^2,
250 = 3,240/d^2
d^2 = 3,240/250 = 12.96
d = 3.6 m.
The second point is 3.6 - 3.0 = 0.6m from the 1st point