When 3A = 4B = 6C — Ratio & Proportion Aptitude Question
When 3A = 4B = 6C: If 3A = 4B = 6C, what is A : B : C? Answer and worked solution on CodeKairo.
- Topic: Ratio & Proportion
- Section: Quantitative Aptitude
- Difficulty: Medium
- Time target: 60 seconds
Question
If 3A = 4B = 6C, what is A : B : C?
Options
- 2 : 3 : 4
- 3 : 4 : 6
- 4 : 3 : 2
- 6 : 4 : 3
Show the answer and the worked solution
Correct answer: C. 4 : 3 : 2
Worked solution
- Let 3A = 4B = 6C = 12 (the LCM of 3, 4 and 6).
- A = 4, B = 3, C = 2.
- So A : B : C = 4 : 3 : 2.
Answer: 4 : 3 : 2.
The idea
Set the common product to the LCM of the coefficients and read off each variable. The ratio comes out inverse to the coefficients, which is why 3 : 4 : 6 is the trap.
Shortcut. When 3A = 4B = 6C the variables go as the reciprocals 1/3 : 1/4 : 1/6; × 12 gives 4 : 3 : 2, and 3 × 4 = 4 × 3 = 6 × 2 confirms it.
Common trap. "3 : 4 : 6" — copying the coefficients; a larger coefficient means a smaller variable, so the order reverses.