Constructing Confidence Intervals, In Exercises 45, use the information to construct 90% and 99% confidence intervals for the population mean. Interpret the results and compare the widths of the confidence intervals.

45. DVR and Other Time-Shifted Viewing, A group of researchers estimates the mean length of time (in minutes) the average U.S. adult spends watching television using digital video recorders (DVRs) and other forms of time-shifted television each day. To do so, the group takes a random sample of 30 U.S. adults and obtains the times (in minutes) below.

29 12 23 24 33 24 28 31 18 27 27 32 17 13 17

12 21 32 26 16 28 28 21 24 29 13 20 13 21 27

From past studies, the research council assumes that s is 6.5 minutes. (Adapted from the Nielsen Company)