If two countries voluntarily trade two goods with one another, the rate of exchange between the goods must fall in between the price ratios that would prevail in the two countries in the absence of trade.

The figure above shows the market demand curve for pizza

a) What is the marginal social benefit of the 20th pizza? b) What is the maximum price a consumer is willing to pay for the 20th pizza? c) If the price of a pizza is $6, what is the consumer surplus of the 20th pizza? d) If the price of a pizza is $10, what is the consumer surplus? e) If the price of a pizza is $6, what is the consumer surplus?

A bank's "required reserves" are:

a. held as deposits with the Federal Reserve System. b. equal to its checkable deposits. c. equal to its transactions deposits. d. none of these.