The following data was obtained from 31 days of operation of a plant for the oxidation of ammonia (NH3) to nitric acid (HNO3). The nitric oxides produced are absorbed in a countercurrent absorption tower. The variable observed "daily stack loss" is an inverse measure of the over-all efficiency of the plant. The data is: 42 7 37 28 18 18 19 20 15 14 14 13 11 12 8 7 8 8 9 15 15 18 20 15 12 10 15 28 25 12 14

Calculate and interpret a 99% CI for true mean stack loss. The sample mean is 16.35484 and sd= 8.312835.