A year ago, the U.S. dollar-Argentine peso (ARS) spot rate was ARS 4.550/$. and the prevailing inflation rates were 10% in Argentina and 2% in the U.S. [Read the quote as "it takes 4.550 ARS to buy one dollar"] A year ago, based on RPPP, you would expect today's spot rate to be (using exactly three decimal places): ARS / $. Suppose that today, the spot rate is ARS 5.450 / $. Relative to what you by might expect using RPPP, the ARS is % versus the $