You contact a random sample of 36 graduates of Western University and learn that their starting salaries averaged $28,000 last year. You then contact a random sample of 40 graduates from Eastern University and find that their average starting salary was $28,800. In each case, the standard deviation of the sample was $1,000.
a) Test the null hypothesis that there is no difference between average salaries received by the graduates of the two schools.
b) What assumptions are necessary for this test?