The caf Den Dripple in Nineveh, Belgium, serves, on average, 60 customers per night. A typical night at Den Dripple is long, about 10 hours.

The café Den Dripple in Nineveh, Belgium, serves, on average, 60 customers per night. A typical night at Den Dripple is long, about 10 hours. At any point in time, there are, on average, 18 customers in the café. Find how long a customer spends, on average, in the restaurant