Question 1139393
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The solution by tutor MathLover1 is not correct.<br>
After finding that the percent increase in price is 21.9%, she incorrectly states<br>
"=> percent increase in price= percent decrease in the buying power of currency"<br>
which is not correct.  As a simple way to see this, suppose the price was doubled, making the increase in price 100%.  Would your buying power be decreased by 100%?<br>
Of course not.  If the price has doubled, your buying power has decreased by 50%, not 100%.<br>
So if you are going to solve the problem the way she started, you need to say your buying power has been reduced by a factor of 100/121.9 = 0.8203.  So the decrease in your buying power is 1-0.8203, which converted to a percentage is 17.97%.<br>
ANSWER: The percentage decrease in buying power over the ten years is 17.97%.