9.36 The author of an entry-level book on using Microsoft Word has carried out a test in which 35 novices were provided with the book, a computer, and the assign- ment of converting a complex handwritten document with text and tables into a Microsoft Word file. The novices required an average time of 105 minutes, with a standard deviation of 20 minutes. Construct and interpret the 90% confidence interval for the population mean time it would take all such novices to complete this task.
9.37 An office equipment manufacturer has developed a new photocopy machine and would like to estimate the average number of 81/2-by-11 copies that can be made using a single bottle of toner. For a simple random sam- ple of 20 bottles of toner, the average was 1535 pages, with a standard deviation of 30 pages. Making and stating whatever assumptions you believe are necessary, con- struct and interpret the 95% confidence interval for the population mean.