Question: According to a study several years ago, the average BMW driver earns $82 600 per year. Suppose a researcher believes that the average annual earnings of a BMW driver are lower now, and he sets up a study in an attempt to prove his theory. He randomly samples 18 BMW drivers and finds out that the average annual salary for this sample is $78 974, with a population standard deviation of $7810. Use α = .01 to test the researcher's theory. Assume annual salaries are normally distributed.