Relating two unknowns — Percentages Aptitude Question
Relating two unknowns: If 8% of x = 4% of y, then 20% of x is what percent of y? Answer and worked solution on CodeKairo.
- Topic: Percentages
- Section: Quantitative Aptitude
- Difficulty: Medium
- Time target: 60 seconds
Question
If 8% of x = 4% of y, then 20% of x is what percent of y?
Options
- 5%
- 10%
- 15%
- 20%
Show the answer and the worked solution
Correct answer: B. 10%
Worked solution
- 8% of x = 4% of y → 8x = 4y → y = 2x.
- 20% of x = 0.2x.
- As a percentage of y: 0.2x / 2x = 0.10 = 10%.
Answer: 10%.
The idea
Reduce the given relation to y in terms of x, then substitute. Keeping everything in one variable makes the final ratio a cancellation rather than a calculation.
Shortcut. 8% of x = 4% of y means y = 2x, so any percentage of x halves when expressed against y: 20% becomes 10%.
Common trap. 20% — carrying the 20% straight across as if x and y were equal, ignoring that y is twice x.