A bank wishing to increase its customer base advertises that it has the fastest service and that virtually all of its customers are served in less than 10 minutes. A management scientist has studied the service times and concluded that service times are exponentially distributed with a mean of 4.5 minutes. Determine what the bank means when it claims 'virtually all' its customers are served in under 10 minutes.

Proportion of customers served in under 10 minutes =