The mean yield of corn in United States is about 120 bushels per acre. A survey of 50 farmers this year gives a sample mean of x = 123.6 bushels per acre. We want to know wether this is good evidence that national mean this year isn't 120 bushels per acre. Suppose that the farmers surveyed are an SRS from the population of all commercial corn growers that standard deviation of yield in this population is σ= 10 bushels per acre. ( Do an hypothesis test. Suppose you didn't have the sample value when you decided to do the test.)