Answer:
15% depreciation
Step-by-step explanation:
the increase/decrease in the effective trade-weighted real exchange rate = (change in the exchange rate with country A x trade weight of country A) + (change in the exchange rate with country B x trade weight of country B) + (change in the exchange rate with country C x trade weight of country C) = (35% x 10%) + (55% x -30%) + (15% x -10%) = 3.5% -16.5% -1.5% = -15% or 15% depreciation
Every time we need to calculate the weighted effect on anything, we must multiply the individual effects by the their specific weight, and then add all the individual results.
In this case, we are measuring the sum of the effects of different changes in the value of the Mexican peso against foreign currencies. In general, the Mexican peso appreciated against one currency but depreciated against two others, but the overall effect is a 15% depreciation.