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The Exchange Rate

2 March, 2015 - 12:11

A country’s exchange rate is the price of its currency in terms of another currency or currencies. On December 12, 2008, for example, the dollar traded for 91.13 Japanese yen, 0.75 euros, 10.11 South African rands, and 13.51 Mexican pesos. There are as many exchange rates for the dollar as there are countries whose currencies exchange for the dollar—roughly 200 of them.

Economists summarize the movement of exchange rates with a trade-weighted exchange rate, which is an index of exchange rates. To calculate a trade-weighted exchange rate index for the U.S. dollar, we select a group of countries, weight the price of the dollar in each country’s currency by the amount of trade between that country and the United States, and then report the price of the dollar based on that trade-weighted average. Because trade-weighted exchange rates are so widely used in reporting currency values, they are often referred to as exchange rates themselves. We will follow that convention in this text.