A senior manager, responsible for a group of 120 junior executives, is interested in the total amount of time per week spent by these people in internal meetings.
A random sample of 35 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 junior executives in the week.