Practice bank

Successive percent changes do not cancel out

QuantPercentsEasy

A store raises the price of a jacket by 20%, then discounts the new price by 20%. The final price is what percent of the original price?

  • A100%
  • B98%
  • C96%
  • D104%
  • E102%

Try it before you scroll. Two minutes on the clock, then commit to an answer.

Correct answer: C

The trap is assuming that +20% and −20% cancel. They do not, because the two percentages apply to different bases.

Let the original price be 100. After the 20% raise, the price is 100 × 1.20 = 120. The discount then takes 20% off 120, not off 100: 120 × 0.80 = 96.

So the final price is 96% of the original, a net decrease of 4%.

A quick rule worth memorizing: a raise of p% followed by a cut of p% always nets to a loss of p²/100 percent. Here 20²/100 = 4%.

  • (A) is the intuitive but wrong “they cancel” answer.
  • (B) and (E) come from arithmetic slips on the second step.
  • (D) treats both percentages as applying to the original price with the raise counted twice.