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Q4) (25 Points) Citrus bank has a single bank clerk. Customers arrive to the bank, according to Poisson process with an average rate of 30 per hour. Each customer requires an average of 1.2 minutes of time in the bank. It is assumed that the customer times in the bank are exponentially distributed. a) What is the average number of customers in the bank in the steady state? b) What is the probability that there are no customers in the bank? c) What is the average time a customer spends in the bank