The number of traffic accidents per day on a certain section of highway in the past was 4 accidents per day in average. Based on this,

a) What is the probability that there may be exactly two traffic accidents tomorrow?
b) What is the probability that there may be no traffic accident tomorrow?
c) What is the probability that there may be more than five traffic accidents tomorrow?
d) What is the probability that there may be no more than two traffic accidents tomorrow?