It is known that, nationally, doctors working for health maintenance organizations (HMOs) average 13.5 years of experience in their specialties, with a standard deviation of 7.6 years. The executive director of an HMO in a Western state is interested in determining whether or not its doctors have less experience than the national average. A random sample of 150 doctors from HMOs shows a mean of only 10.9 years of experience.
a. State the research and the null hypotheses to test whether or not doctors in this HMO have less experience than the national average.
b. Using an alpha level of .01, make this test.