For the cellular phone in Problem 2.6.6, express the monthly cost C as a function of M, the number of minutes used. What is the expected monthly cost E[C]?
Problem 2.6.6
Suppose that a cellular phone costs $20 per month with 30 minutes of use included and that each additional minute of use costs $0.50. If the number of minutes you use in a month is a geometric random variable M with expected value of E[M] = 1/p = 30 minutes, what is the PMF of C, the cost of the phone for one month?