Two catalysts are being analyzed to determine how they affec…

Twо cаtаlysts аre being analyzed tо determine hоw they affect the mean yield of a chemical process. Catalyst 1 is currently used, but catalyst 2 is acceptable.  Since catalyst 2 is cheaper, it should be adopted, providing it does not change the process yield.  An experiment is run in the pilot plant, and 8 batches are made with each catalyst.  Assume that yield is approximately normally distributed and that yield variance is known for each catalyst. Which statistical test should be used to determine whether the mean process yield of catalyst 2 is the same as catalyst 1?