A manufacturer of cell phones would like to estimate how much longer the battery lasts in their model 10 phone than in their model 9 phone. To estimate this difference, they randomly select 40 cell phones of each model from the production line. They subject each phone to a standard battery life test. The 40 model 10 phones have a mean battery life of 14.4 hours with a standard deviation of 2.1 hours. The 40 model 9 phones have a mean battery life of 12.8 hours with a standard deviation of 2.3 hours. The conditions for inference have been met. What is the correct 95% confidence interval for the difference in the population means?Find the t-table here.