Three discounts as one — Profit & Loss Aptitude Question
Three discounts as one: Successive discounts of 10%, 20% and 30% are equivalent to a single discount of: Answer and worked solution on CodeKairo.
- Topic: Profit & Loss
- Section: Quantitative Aptitude
- Difficulty: Medium
- Time target: 60 seconds
Question
Successive discounts of 10%, 20% and 30% are equivalent to a single discount of:
Options
- 45.5%
- 49.6%
- 52%
- 60%
Show the answer and the worked solution
Correct answer: B. 49.6%
Worked solution
- Remaining fraction = 0.90 × 0.80 × 0.70 = 0.504.
- Total discount = 1 − 0.504 = 49.6%.
Answer: 49.6%.
The idea
Chain the surviving fractions rather than the discounts. Adding the three (60%) always overstates the true reduction.
Shortcut. Merge two at a time with a + b − ab/100: 10 and 20 give 28, then 28 and 30 give 58 − 8.4 = 49.6%.
Common trap. 60% — adding 10 + 20 + 30, as if each discount came off the original price.