An archer shoots an arrow at a circular target with a
radius of 50 cm. If the arrow hits the target, the distance between
the point of impact and the center of the target is measured.
Suppose that this distance R has a cumulative distribution function
of
F(r) = 1.0007 – [125.09 / (r+5)3] for 0 ≤ r ≤ 50
What is the expected distance between the point of impact and the
center of the target?