13. Benson Racing is training a new pit crew for its racing team.

For its first practice run, the pit crew is able to complete all the tasks in exactly 30 seconds—not exactly world-class. The second time around the crew shaves 4.5 seconds off its time.

a. (*) Estimate the learning rate for the pit crew based on the times for the first two practice runs.

b. (**) Mark Benson, owner of Benson Racing, says that the pit crew must be able to complete all the tasks in less than 15 seconds in order to be competitive. Based on your answer to Part

a, how many times will the pit crew need to practice before it breaks the 15-second barrier?

c. (**) Is it realistic to expect the pit crew to experience learning improvements indefinitely? Explain.