Answer
$I=3.97 \times 10^{-5}W/m^2$
Work Step by Step
To find the intensity at $30.0$ m, a formula using intensity, power, and distance from the source must be used. This is $$I=\frac{P}{A}=\frac{P}{4\pi R^2}$$ To find the power, use $I=0.960 \times 10^{-3} W/m^2$ and $R=6.10m$. Solve for $P$ to get $$P=4 \pi R^2 I$$ Substituting values of $I=0.960 \times 10^{-3} W/m^2$ and $R=6.10m$ yields $$P=4 \pi (6.10m)^2 (0.960 \times 10^{-3}W/m^2)=.449W$$ Using values of $P=0.449W$ and $R=30.0m$ yields $$I=\frac{0.449W}{4\pi (30.0m)^2}=3.97 \times 10^{-5}W/m^2$$
