In an Ordinary 8-Hour Day, Roto-Drains Receives Calls for Emergency

Multiple Choice

In an ordinary 8-hour day, Roto-Drains receives calls for emergency service at an average rate of 1 per hour (otherwise, the calls appear to be random and independent) .The owner currently has a crew of technicians capable of handling up to (and including) nine emergencies per day.What is the probability that on a random day there are more calls than her crew can handle?

A) .2833
B) .2617
C) .3419
D) .2509
E) .2864