4. According to economist Colin Camerer of the California Institute of Technology, many New York taxi drivers decide when to finish work for the day by setting an income goal for themselves. Once they reach it, they stop working.

a. Is that what you would expect if the drivers are rational?

b. Prospect theory suggests that people gain less utility from winning a certain sum of money than the utility they would lose if they lost that same sum. How can prospect theory explain the behavior of taxi drivers?