Listed below are 12 lengths (in minutes) of randomly selected movies from Data Set 9 in Appendix B.

a. Construct a 99% confidence interval estimate of the mean length of all movies.

b. Assuming that it takes 30 min to empty a theater after a movie, clean it, allow time for the next audience to enter, and show previews, what is the minimum time that a theater manager should plan between start times of movies, assuming that this time will be sufficient for typical movies?

110 96 125 94 132 120 136 154 149 94 119 132