The largest single source of revenue for the federal government is the

Economist Jan Tinbergen developed a formula, called ______, to predict which nations would engage in bilateral trade.

a. the trade deficit equation b. the index of equality c. the Tinbergen ratio d. the gravity equation of trade

According to the diagram in the above figure, what is the marginal benefit of consuming the 3 millionth gallon of gasoline per month?

A) 5 pounds of shrimp per gallon of gasoline B) 3 pounds of shrimp per gallon of gasoline C) 2 pounds of shrimp per gallon of gasoline D) 1 pound of shrimp per gallon of gasoline