A Burger King processes on average $1500$ customers$/$day$.$ On average, there are $50$ customers

in the store at a time. Customers may be waiting to place an order, placing an order, waiting for

the order to be ready, eating, and so on$.$ What is the average time that a customer spends in

the store? At any given time, there are $50$ customers in the store. How often can the

manager of the store expect that the entire group of $50$ customers would be entirely replaced

$(50$ new customers are in the store$)?$