Afarmer is interested in maximizing the wheat yield in his fields. he tries two different varieties of wheat and records the wheat yield after a few months. he got the following results: variety a: 31, 39.5, 30.5, 35.5, 37 variety b: 28, 34, 24.5, 31.5, 31.5, 25.5, 31, 25, 33, 29.5 what type of hypothesis test should he perform?