全英某顶级经济系院校的本科基础题，觉得难度没什么，但是却大半个系的学生考40分以下...难道全是判分严格的问题？？发上来大家一起看看~ 不知各位觉得哪道有难度？全是判断+证明的题 P.S小弟第一次发帖，要是发错地方了还请包涵

1) If a country is operating inside its Production Possibility Frontier, the opportunity cost of one of the goods must be zero.

2）A consumer spends all his income on two goods. If the price of both goods falls the consumer’s budget line shift outwards parallel.

3）In a market we observe a rise in the equilibrium price and a fall in the equilibrium quantity. Consumer surplus must have fallen.

4)An individual consumes two goods that are perfect complements. The substitution effect of a fall in the price of one of the goods is zero.

5)An individual spends all her income on two goods, X and Y. The price of X falls but this individual buys the same amount of X as previously (income and the price of Y remain the same as before). Y must be a normal good.

6)A lottery charges ₤10 for a ticket and pays a prize of ₤20 on 50 percent of the tickets. A risk-averse individual will not buy a ticket.

7)Adverse selection occurs when an individual takes greater risks if she is covered by insurance.

8)A perfectly competitive industry consists of identical firms with ‘U’ shaped long run average cost curves. An increase in demand has no effect on each of the original firms’ output in the long run.

9)If a firm in the long run sets its Marginal Rate of Technical Substitution equal to the ratio of factor prices then it must be maximising its profit.

10)A profit maximising monopolist produces at a point where demand is elastic.

11) The demand for potatoes is QD = 160 – 2P, and supply is QS = – 40 + 2P where prices (P) are in pounds and quantities (Q) are in tonnes.
a)Find the value of consumer and producer surplus in this market. [5 marks]
b)The government decides to give a subsidy to producers of ₤20 per tonne on this essential food. How much does consumer and producer surplus change? Calculate the welfare loss to society and illustrate this on a diagram. [8 marks]
c)Instead of the policy in (b), the government decides to open this market to international trade (previously imports were banned). The world price of potatoes is ₤40 per tonne and world supply is perfectly elastic. Compare the social welfare from this policy with that under (a), and illustrate using a diagram. [7 marks]
d) Is it worth opening trade as in (c ) but compensating the farmers as in (b) above? [5 marks]