The average starting salary of a random sample of 100 high school students was found to be $31,840. The population standard deviation for all such individuals is known to be $9,840.

a. Ten years ago, the average starting salary was $25,000.  Does the sample data support the claim that the starting salary for this group has increased?  Use alpha = 0.05.

b. Describe in general Type I and Type II errors and the Power of the test.

c. Describe in the context of the problem Type I and Type II error, and the Power of the test.