I need help with question C

Janton's Department Store in Stark, Ohio, maintains a successful catalog saies department in which a derk takes orders by talephone. If the cierk is occupied on one ine, incoming phone cals to the catalog department are answered outomatically by a recording machine and anked to wait. As soon as the deek is free, the paty who has wated the longost is tranaternd and serviced trat. Calls come in at a rate of about 11 per hour. The denk can take an order in an average of 4.0 minules. Cals tered to follow a Poisson distrbution, and service times terd to be negative expontential The coet of the cleck is 58 per hour, but because of lost goodwill and taies, Janton's loses about 530 per bour of cuskirser time scent wasing for the dierk to takib an order. b) The average number of callers wating to place an order = 2 callen (pound your meponse to two decimal placen). two decimal plinces)