Answer
25 mi/hr
Work Step by Step
We know that if point $P$ is a point on a circle of radius $r$, and $P$ moves in a distance $s$ on the circumference of the circle in an amount of time $t$, then the linear velocity, $v$, of $P$ is calculated as $v=\frac{s}{t}$.
We are given that $s=100$ mi and $t=4$ hr.
Therefore, $v=\frac{100mi}{4hr}=\frac{100mi\div4}{4hr\div4}=\frac{25mi}{1hr}=25$ mi/hr.