A catalog company 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

A catalog company 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. what proportion of customers having to hold more than 4.5 minutes will hang up before placing an order