5. In one area, monthly incomes of college graduates have a standard deviation of $650. It is believed that the standard deviation of monthly incomes of non-college graduates is higher. A sample of 21 non-college graduates are randomly selected and found to have a standard deviation of $950. Does the evidence suggest that the monthly incomes of non-college graduates have a higher standard deviation? Use = 0.05 and the rejection region method.

a) State H0, Ha.

b) State the test you will use. (z-test, t-test, 1-prop-Ztest, etc)

c) Sketch your rejection region and label the cutoff(s).

d) Calculate your test statistic.

e) State your decision.

f) Interpret your decision in terms of the original problem