17.28 Of the 300 pages in a particular book, 180 pages are primarily nontechnical, while the remainder of the pages are technical. Independent random samples of technical and nontechnical pages were taken, and the numbers of errors per page were recorded. The results are summarized in the following table:

Technical Nontechnical Ni 120 180 ni 20 20 xi 1.6 0.74 si 0.98 0.56

a. Find a 95% confidence interval for the mean number of errors per page in this book.

b. Find a 99% confidence interval for the total number of errors in the book.