Joe’s wealth is $100 and he is an expected utility maximizer with a
utility function U(W) = W1/2. Joe is afraid of oversleeping his
economics exam. He figures there is only a 1 in 10 chance that he
will, but if he does, it will cost him $100 in fees to the
university for taking an exam late. Joe’s neighbor, Mary, never
oversleeps. She offers to wake him one hour before the test, but he
must pay her for this service. What is the most that Joe would be
willing to pay for this wake- up service?