A Pizza store has 4 operators that take calls from customers. Each call lasts 5 minutes, on

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Question:

A Pizza store has 4 operators that take calls from customers. Each call lasts 5 minutes, on average, with a standard deviation of 5 minutes. A call arrives, on average, every 3 minutes, with a standard deviation of 3 minutes. On average, how many minutes does a customer wait before talking to an operator? Show work please.