State the null and alternative hypotheses to be used in testing the following claims, and determine generally where the critical region is located:
(a) At most, 20% of next year's wheat, crop will be exported to the Soviet Union.
(b) On the average, American homemakers drink 3 cups of coffee per day.
(c) The proportion of graduates in Virginia this year majoring in the social sciences is at least. 0.15.
(d) The average donation to the American Lung Association is no more than $10.
(e) Residents in suburban Richmond commute, on the average, 15 kilometers to their place of employment.