Unlike countries with currency problems, China has used a fixed exchange rate to keep the value of

Question:

Unlike countries with currency problems, China has used a fixed to keep the value of its currency below its market level.
a. Why is it easier for a country to undervalue a currency than to overvalue it?
b. Why does China’s exchange-rate policy affect its purchase of U.S. Treasury securities?
c. What is likely to happen to China’s imports, exports, and purchases of U.S. securities if the is allowed to float?
Exchange Rate
The value of one currency for the purpose of conversion to another. Exchange Rate means on any day, for purposes of determining the Dollar Equivalent of any currency other than Dollars, the rate at which such currency may be exchanged into Dollars...