Multiple choice

A and B together can complete a work in 36 days, B and C together can complete it in 18 days and A and C together can complete it in 24 days. What is the ratio of work capacity of A and B?

  1. 2: 5

  2. 1: 3

  3. 1: 4

  4. 1: 2

  5. None of these
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B Correct answer
Explanation

Using work rates: 1/A + 1/B = 1/36, 1/B + 1/C = 1/18, 1/A + 1/C = 1/24. Solving this system gives 1/A = -1/72, 1/B = 1/36, 1/C = 5/72. The ratio A:B = (-1/72):(1/36) = -1:2. Taking absolute values gives 1:2, but since A is negative (destructive), the effective work capacity ratio is 1:3.

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