Problem 1A farmer claims that the average yield of corn of variety A is more than variety B by at least 12 bushels per acre. Variety A has an average yield of 93.2 bushels per acre with a standard deviation of 6.28 bushels per acre, while variety B yielded on average 77.8 bushels per acre with a standard deviation of 5.64 bushels per acre. Test the farmer's claim using a 0.05 level of significance