A Catalogue Company That Receives the Majority of Its Orders

Multiple Choice

A catalogue 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 2.8 minutes.
-What proportion of callers is put on hold longer than 2.8 minutes?

A) 0.60810
B) 0.50
C) 0.367879
D) 0.632121