The time in (seconds) that it takes a librarian to locate an entry in a file of records on checked-out books has an exponential distribution of lambda = .05. In the long run, what proportion of the...

The time in (seconds) that it takes a librarian to locate an entry in a file of records on checked-out books has an exponential distribution of lambda = .05.  In the long run, what proportion of the time will you have to wait more than the average wait time?