4. The relationship between nominal exchange rate and relative prices. From the annual observations from 1980 to 1994, the following regression results were obtained, where Y = exchange rate of the German mark to the U.S. dollar (GM/$) and X = ratio of the U.S. consumer price index to the German consumer price index; that is, X represents the relative prices in the two countries: Y" t = 6.682 - 4.318X, r ? - 0.528 se - (1.22) (1.333) a. Interpret this regression. How would you interpret r 2? b. Does the negative value of X, make economic sense? 10