CA Foundation · Quantitative Aptitude · Ratio and Proportion, Indices and Logarithms
If a : b = b : c = 2 : 3, then a : c equals:
a : c equals 4 : 9. Multiplying a/b = 2/3 by b/c = 2/3 cancels b and gives a/c = 4/9, which is the duplicate ratio of 2 : 3 as expected in a continued proportion.
- A2 : 3
- B4 : 9Correct
- C8 : 27
- D4 : 6 : 9
Explanation
a/b = 2/3 and b/c = 2/3, so a/c = (a/b)(b/c) = 4/9. Option 2 : 3 is wrong because it ignores the compounding; 8 : 27 would be the ratio for a three-step chain.
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