Ex. 5.8 Let X be a random variable equal to the number of misprints in the book containing 100 pages, where on average there is one error on 20 pages. Let Y be the number of printing errors in a booklet containing 10 pages, where on average there are 2 errors on 5 pages. What is the probability that the total number of errors in both: the book and the booklet does not exceed 7? What assumptions have you made?