15. The average speed that a tsunami (a large tidal wave) travels is represented
by the function s = (2002)1/2, where s is the speed (in miles per hour) that
the tsunami is traveling and d is the average depth (in feet) of the wave.
a. Find the inverse of the function.
b. Find the average depth of the tsunami when the recorded speed of the
wave is 250 miles per hour.