P1ease show the formulas that need to be used as well as an explanation on how to apply them.

In order to determine the average weight of carry-on luggage by passengers in airplanes, a sample of 152 pieces of carry-on luggage was collected and weighed. The average weight was 37.9 pounds. Assume that we know the standard deviation of the population to be 9 pounds. Determine a 90% confidence interval estimate for the mean weight of the carry-on luggage.