A chain of comparisons — Percentages Aptitude Question
A chain of comparisons: A's marks are 20% more than B's, and B's marks are 25% less than C's. Answer and worked solution on CodeKairo.
- Topic: Percentages
- Section: Quantitative Aptitude
- Difficulty: Medium
- Time target: 60 seconds
Question
A's marks are 20% more than B's, and B's marks are 25% less than C's. A's marks are what percent of C's?
Options
- 85%
- 90%
- 95%
- 105%
Show the answer and the worked solution
Correct answer: B. 90%
Worked solution
- Let C = 100. Then B = 75 (25% less).
- A = 1.20 × 75 = 90.
- A as a percentage of C = 90%.
Answer: 90%.
The idea
Anchor the number at the far end of the chain and work towards the one you are asked about. Adding and subtracting the percentages (20 − 25 = −5) gives 95% and is wrong.
Shortcut. Multiply the factors: 6/5 × 3/4 = 18/20 = 90%.
Common trap. 95% — netting the percentages (+20 − 25 = −5) as if both were measured on C.