The state department of agriculture is trying to determine the average corn yield for farmers in the state. They take a sample of 40 farmers and determine that the average yield was 151.2 bushels per acre. If the population standard deviation is 12.3 bushels per acre, create a 90% confidence interval for the mean yield in the state this season.
What is the margin of error? Create a 99% confidence interval for the mean yield per acre.