A newspaper finds that the mean number of typographical errors per page is four. Find the probability that the number of typographical errors found on any given page is
(a) Exactly three,
(b) At most three,
(c) More than three.
Find the indicated probabilities using the geometric distribution, the Poisson distribution, or the binomial distribution. Then determine whether the events are unusual. If convenient, use a table or technology to find the probabilities.