20% of A equals 30% of B — Percentages Aptitude Question
20% of A equals 30% of B: If 20% of A = 30% of B, then A : B is: Answer and worked solution on CodeKairo.
- Topic: Percentages
- Section: Quantitative Aptitude
- Difficulty: Easy
- Time target: 45 seconds
Question
If 20% of A = 30% of B, then A : B is:
Options
- 2 : 3
- 3 : 2
- 4 : 5
- 5 : 4
Show the answer and the worked solution
Correct answer: B. 3 : 2
Worked solution
- 0.2A = 0.3B → A/B = 0.3/0.2 = 3/2.
- So A : B = 3 : 2.
Answer: 3 : 2.
The idea
When x% of A = y% of B, the ratio A : B is y : x — the percentages swap sides. Writing the equation out prevents inverting it by accident.
Shortcut. The smaller percentage goes with the larger quantity, so A > B: only 3 : 2 and 5 : 4 qualify, and 0.2 × 3 = 0.3 × 2 settles it.
Common trap. "2 : 3" — copying the percentages across in order (20 : 30) instead of swapping them.