13. If the real exchange rate for coal is 1.5, the price of coal in the United States is $50 per ton, and the price of coal in Britain is 20 British pounds per ton, what is the nominal exchange rate? a. 15/4 or 3.75 pounds per dollar b. 5/3 or 1.67 pounds per dollar c. 3/5 or 0.6 pounds per dollar d. 4/15 or 2.67 pounds per dollar