A senior manager, responsible for a group of 120 junior executives, is interested in the to- tal amount of time per week spent by these people in internal meetings. A random sample of thirty-five of these executives was asked to keep diary records during the next week. When the results were analyzed, it was found that these sample members spent a total of 143 hours in internal meetings. The sample standard deviation was 3.1 hours. Find a 90% confidence interval for the total number of hours spent in internal meetings by all 120 ju- nior executives in the week.