a. Explain intuitively how the choice of calling plan should depend on what the expected call duration is.
b. Which plan is better if expected call duration is 10 minutes? 15 minutes? [Hint: Let h1(x) denote the cost for the first plan when call duration is x minutes and let h2(x) be the cost function for the second plan. Give expressions for these two cost functions, and then determine the expected cost for each plan.]