A Study Conducted by Uni-Mart, a Mail-Order Department Store, Reveals

Short Answer

A study conducted by Uni-Mart, a mail-order department store, reveals that the time intervals in minutes between incoming telephone calls on its toll-free 600 line between 10 A.M. and 3 P.M. are exponentially distributed with probability density function .
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What is the probability that the time interval between successive calls is more than 5 min? Give the answer to four decimal places, if necessary.