Answer
Total Broadcast Area: 70,650 mi$^{2}$
Work Step by Step
We will treat the distance of the radio signal as the radius of a circle since it is the same in all directions.
Area of a Circle: $A$ = $\pi$$r$$^{2}$
Therefore:
$A$ = $\pi$(150 mi)$^{2}$
$A$ = 70,650 mi$^{2}$
