Question 9 2 pts A bank teller serves customers standing in the queue one by one. Suppose that the service time X,- for customer i has mean 3 minutes and variance 1. We assume that service times for different bank customers are independent. Approximate the probability that the total time the bank teller spends sewing 50 customers is at least 158 minutes. Give your answer accurate to 4 decimal places. Question 10 2 pts Let X be an exponential random variable with parameter 11 = 1/2. Use Markov's inequality to nd an upper bound for P(XZ7). Give your answer accurate to 2 decimal places