These can be calculated directly.
p(No more than 2) = p(0)+p(1)+p(2)
p(at least 2) = 1- (p(0)+p(1))
Let's see what you get.
Customer arrivals at a checkout counter have a Poisson distribution with an average of 7 per hour. For a given hour, find the probabilities of the following events:
a) Exactly seven customers arrive
b) No more than two customers arrive
c) At least two customers arrive
Can someone help me figure this out? I don't know how to approach this problem.