Answer:

There are 2 ways to solve this:

1. Similar to the solution of Q1 (b)

I =P/A = 10/[4p (10)^{2}] =
7.96X10^{-3} W/m^{2}

2. Remembering from Q1 (b) that the intensity at 1 m was 0.796
W/m^{2} and using the inverse square law:

I =P/A = 0.796/10^{2} = 7.96X10^{-3} W/m^{2}