Example 2 A Gallup Poll of 547 adult Americans employed full or part time conducted August 13-16, 2007 asked, "How much total time in minutes do you spend commuting to and from work in a typical day?" Survey results indicated that * = 45.6 minutes and s = 31.4 minutes. a) Construct and interpret a 90% confidence interval for the mean commute time of adult Americans employed full or part time. b) Do you think that it would be likely to have a mean commute time less than 40 minutes? Why