A certain process for etching printed circuit boards requires the use of a catalyst. We want to compare two catalysts to determine if removal of a given amount of photoresist requires the same amount of time or not of immersion in each case. To do this, 12 tests are carried out with catalyst 1. The immersion time for this sample has an average of 24.6 minutes and a standard deviation of 0.85 minutes. Similarly, 15 trials are carried out. with Catalyst 2. The immersion time for this sample shows a mean of 22.1 minutes and a standard deviation of 0.98 minutes. 1. Establish a 95% confidence interval of the difference between the means of these two independent populations assumed to follow the normal pattern with the same standard deviation. 2. Interpret this result.