Answer:
4976.28 square miles (nearest hundredth)
Step-by-step explanation:
[tex]\textsf{Area of a circle}=\pi r^2 \quad \textsf{(where r is the radius)}[/tex]
FM radio station
Given:
[tex]\implies \textsf{Area}=\pi (40)^2=1600 \pi \: \sf miles^2[/tex]
AM radio station
Given:
[tex]\implies \textsf{Area}=\pi (4)^2=16 \pi \: \sf miles^2[/tex]
Difference:
[tex]\begin{aligned}\implies \textsf{FM area - AM area} & =1600 \pi - 16 \pi\\ &= 1584 \pi\\ & =4976.23\:\textsf{square miles (nearest hundredth)}\end{aligned}[/tex]