39. Over a long period of time, the global supply of agricultural products has increased significantly, while farmers' incomes have decreased significantly. This can be explained by A. The demand for agricultural products has decreased during the past few decades
B. support for agricultural products reduces farmers' income
C. total revenue from agriculture decreases as output increases because the demand for most agricultural products is inelastic
D. all of the above

47. The marginal rate of substitution between two goods is always equal to
A. the price of one good divided by the price of another good
B. the marginal utility of one good multiplied by the marginal utility of the other
C. the marginal utility of one good divided by the marginal utility of the other
D. Both a and c are correct

48. When the government redistributes income from the rich to the poor
A. both efficiency and equity are improved
B. Efficiency improves but equity does not
C. equity improves but efficiency does not
D. neither efficiency nor equity has improved

49. Rational humans make marginal decisions by comparison
A. total cost and total benefit
B. Additional costs and additional benefits
C. average cost and average benefit
D. opportunity cost and opportunity benefit

50. Which of the following is not an example of an opportunity cost of going to college?
A. Sleep is gained without going to school
B. Go to a party if you don't have to study for an exam
C. How much money can be earned without going to college
D. The amount of rent to pay when attending college

51. Which of the following is not true about most economic models?
A. they ignore many features of the real world economy
B. they include equations and graphs
C. they contribute little to the understanding of economists and the real world
D. in building models, economists make assumptions

55. The slope of the budget constraint is all of the following, EXCEPT
A. relative price of two goods
B. the rates at which consumers can afford to buy one good instead of another
C. unchanged
D. marginal rate of substitution

Thank you