Distance to Lightning When a bolt of lightning strikes in the distance, there is oft...

Distance to Lightning When a bolt of lightning strikes in the distance, there is often a delay between seeing the lightning and hearing the thunder. The function defined by computes the approximate distance in miles between an observer and a bolt of lightning when the delay is x seconds. (Source: Weidner, R., and R. Sells, Elementary Classical Physics, Allyn and Bacon, Inc.)

(a) Find f(15) and interpret the result.

(b) Graph y = f(x). Let the domain of f be [0, 20].