7. Mr. Jones is at a train station, waiting to make a phone call. There are two public telephone booths next to each other and occupied by two persons, say A and B. If the duration of each telephone call is an exponential random variable with λ = 1/8, using simulation, approximate the probability that among Mr. Jones, A, and B, Mr. Jones is not the last person to finish his call. 8. The distributions of students’grades for probability and calculus at a certain university are, respectively, N (65, 400) and N (72, 450). Dr. Olwell teaches a calculus class with 28 and a probability class with 22 students. Write an algorithm to simulate the probability that the difference between the averages of the final grades of the classes of Dr. Olwell is at least 2.