Two discounts as one — Profit & Loss Aptitude Question
Two discounts as one: Successive discounts of 20% and 10% are equivalent to a single discount of: Answer and worked solution on CodeKairo.
- Topic: Profit & Loss
- Section: Quantitative Aptitude
- Difficulty: Easy
- Time target: 40 seconds
Question
Successive discounts of 20% and 10% are equivalent to a single discount of:
Options
- 25%
- 28%
- 30%
- 32%
Show the answer and the worked solution
Correct answer: B. 28%
Worked solution
- After 20% off, 80% remains; after a further 10% off, 90% of that remains.
- Remaining = 0.8 × 0.9 = 0.72, so the total discount is 1 − 0.72 = 28%.
Answer: 28%.
The idea
Successive discounts of a% and b% equal a single discount of a + b − ab/100. Two discounts never add up to their sum.
Shortcut. The second 10% comes off 80, not 100, so it removes only 8: 20 + 8 = 28%.
Common trap. 30% — adding the two discounts (20 + 10); the second applies to the already reduced price.