In order to determine the average weight of carry-on luggage by passengers in airplanes, a sample of 25 pieces of carry-on luggage was collected and weighed. The average weight was 18 pounds. Assume that we know the standard deviation of the population to be 7.5 pounds. Also, assume the population is normally distributed. Determine a 96% condence interval estimate for the population mean weight of the carry on luggage. {provide your answer in the exact format: (lower , upper], use two decimal place]. 3