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2) This question concerns the mechanism of a reserve currency standard.
Two countries, X and Y, have two currencies, x and y, fixed to the reserve currency, the U.S.
dollar. Suppose the exchange rate between x and the U.S. dollar is 3x per dollar. Suppose the
exchange rate between y and the U.S. dollar is 5y per dollar. Explain (using numbers) the
mechanism if the x-y exchange rate was 0.5 x per y.
Answer: At this exchange rate, an investor can make an arbitrage profit by selling $100 to the
central bank of X (receiving 300 x), then selling your 300 x to the foreign exchange market for
300 x/(0.5 x per y) = 600 y, then buying U.S. dollars in the amount of $120 from the central bank
of Y. Thus the foreign exchange market will bid the x-y exchange rate up to 0.6 x per y.
Page Ref: 518-519
Difficulty: Difficult
3) This question concerns the mechanism of a reserve currency standard.
Two countries, X and Y, have two currencies, x and y, fixed to the reserve currency, the U.S.
dollar. Suppose the exchange rate between x and the U.S. dollar is 3x per dollar. Suppose the
exchange rate between y and the U.S. dollar is 5y per dollar. Explain (using numbers) the
mechanism if the x-y exchange rate was 0.8 x per y.
Answer: At this exchange rate, an investor can make an arbitrage profit by selling $100 to the
central bank of Y (receiving 500 y), then selling this 500 y to the foreign exchange market for
500 y/(0.8 x per y) = 400 x, then buying $133.33 U.S. dollars from the central bank of X with
this 400 x. Thus the foreign exchange market will bid the x-y exchange rate down to 0.6.
Page Ref: 518-519
Difficulty: Difficult
4) Explain how a country whose currency is the reserve currency can use monetary policy for
macroeconomic stabilization. In particular, explain the result if that country doubled its domestic
money supply.
Answer: The immediate result of the doubling of the money supply in the reserve currency’s
country will be able to increase the exchange rate between the reserve currency and all other
currencies. However, all other countries must fix their exchange rate to the reserve currency, so
they will purchase the reserve currency and hold it as official international reserves (thus
increase their own money supply) until the exchange rate has returned to normal. Thus, the
reserve country has the power to affect its own economy and all other countries must adjust in
response.
Page Ref: 518-519
Difficulty: Moderate