Bunuel wrote:
During a sale, the price of a pair of shoes is marked down 10% from the regular price. After the sale ends, the price goes back to the original price. What is the percent of increase to the nearest percent from the sale price back to the regular price for the shoes?
A. 9%
B. 10%
C. 11%
D. 15%
E. 90%
The multiplier for percent increase to get back to original (of 100 percent = 1), is the inverse of the multiplier for the original percent decrease. Then subtract 1.
Percent decrease * percent increase = 1
Ten percent decrease = \(\frac{9}{10}\)
Flip the fraction above to determine the percent by which the decreased value must increase to get to original: \(\frac{10}{9}\) = 1.11 - 1 = .11
11%
Example:
Assume shoes cost 10
10% discount is \(\frac{9}{10}\)(10) = new price is 9
What percent increase to get back to 10?
9 * \(\frac{10}{9}\) = 10
\(\frac{10}{9}\) = 1.11, subtract 1 (because it already includes the 9) = 11%
Answer C
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