A Company That Receives the Majority of Its Orders by Telephone

A 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
Waiting time was found to be a variable best approximated by an exponential distribution with a
Mean length of waiting time equal to 2.8 minutes (i.e.the mean number of calls answered in a
Minute is 1/2.8) .What is the probability that a randomly selected caller is placed on hold fewer
Than 7 minutes?

A) 0.0009119
B) 0.082085
C) 0.917915
D) 0.9990881