Phone Orders the L.L.Bean Catalog Department That Receives the Majority of Majority

Essay

Phone Orders
The L.L.Bean catalog department that receives the majority of its orders by telephone conducted a study to determine how long customers were willing to wait on hold before ordering a product.The length of time was found to be a random variable best approximated by an exponential distribution with a mean equal to 3 minutes.
-{Phone Orders Narrative} What proportion of callers are put on hold longer than 3 minutes?