CT Commercial Bank is the only bank in the town of Kuching, Sarawak. On a typical Friday, an average of 12 customers per hour arrive at the bank to transact business. There is currently one teller at the bank, and the average time required to transact business is 4 minutes. It is assumed that service times may be described by the negative exponential distribution. If a single teller is used a) Compute the average time that customers must wait before transact the business. b) Calculate the value of probability that there are no customer transact the business in the system. c) Compute the average time that a customer transact the business in the system.

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A self-service store employs one cashier at its counter. Nine customers 'arrive on an average every 5 minutes while the cashier can serve 10 customers in 5 minutes. Assuming Poisson distribution for arrival rate and exponential distribution for service time, find 1. Average number of customers in the system. 2. Average number of customers in the queue or average queue length. 3. Average time a customer spends in the system. 4. Average time a customer waits before being served. A.1