Among the most exciting aspects of a university professor's life are the departmental meetings where such critical issues as the color the walls will be painted and who gets a new desk are decided. a sample of 20 professors was asked how many hours per year are devoted to such meetings. the responses are listed below. assuming that the variable is normally distributed with a standard deviation of 6 hours, estimate the mean number of hours spent at departmental meetings by all professors. use a confidence level of 95%.