Two reductions as one — Percentages Aptitude Question
Two reductions as one: Successive reductions of 10% and 20% are together equivalent to a single reduction of: Answer and worked solution on CodeKairo.
- Topic: Percentages
- Section: Quantitative Aptitude
- Difficulty: Easy
- Time target: 45 seconds
Question
Successive reductions of 10% and 20% are together equivalent to a single reduction of:
Options
- 26%
- 28%
- 30%
- 32%
Show the answer and the worked solution
Correct answer: B. 28%
Worked solution
- Remaining fraction = 0.90 × 0.80 = 0.72.
- Total reduction = 1 − 0.72 = 28%.
Answer: 28%.
The idea
Successive reductions of a% and b% equal a single reduction of a + b − ab/100. They never simply add.
Shortcut. The 20% cut acts on only 90% of the price, so it removes 18 points, not 20: 10 + 18 = 28%.
Common trap. 30% — adding the two reductions (10 + 20), as though both came off the original price.