The Manager of the Local Grocery Store Has Determined That

The manager of the local grocery store has determined that, on average, 4 customers use the service desk every half-hour. Assume that the number of customers using the service desk has a Poisson distribution. What is the probability that during a randomly selected half-hour period, no more than 2 customers use the service desk?

A) .2381
B) .1465
C) .7619
D) .9084
E) .0916