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A price rose from 80 dollars to 92 dollars. What was the percent increase?
AIt rose by 12 percent
BIt rose by 13 percent
CIt rose by 20 percent
DIt rose by 15 percent
Answer & Solution
Correct answer: D. It rose by 15 percent
1. First find the amount of change, the new amount minus the original amount.
2. That is 92 dollars minus 80 dollars, which is 12 dollars.
3. Now ask what percent 12 is of the original amount, 80.
4. Write it as 12 equals p times 80.
5. Divide both sides by 80 to get p equal to 0.15.
6. Changing to percent form gives a 15 percent increase.
7. Answering 12 percent reports the amount of change in dollars as if it were a percent.
8. Answering 13 percent divides the change by the new amount rather than the original.
9. Answering 20 percent takes the change as a fraction of 60, a number never given.
_Source: OpenStax Intermediate Algebra (CC BY 4.0), Ch 2 "Solving Linear Equations", section 2.2 Use a Problem Solving Strategy_