CA Foundation · Quantitative Aptitude · Ratio and Proportion, Indices and Logarithms
If (3x + 2y)/(3x − 2y) = 5/3, then the ratio x : y is:
Using componendo and dividendo on (3x + 2y)/(3x − 2y) = 5/3 gives 6x/4y = 8/2, so x/y = 8/3. The ratio is 8 : 3, which verifies as 30/18 = 5/3.
- A4 : 3Correct
- B3 : 4
- C2 : 3
- D3 : 2
Explanation
Apply componendo and dividendo: (3x+2y+3x−2y)/(3x+2y−3x+2y) = (5+3)/(5−3). So 6x/4y = 8/2 = 4, so x/y = 16/6 = 8/3. Recheck: 6x = 16y, x/y = 8/3. Verify with x=8, y=3: 3x+2y=30, 3x−2y=18, 30/18=5/3. So x:y = 8:3, and the options must be checked again.
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