Multiple choice

‘A’ can do a work in 48 days, ‘B’ is 20% more efficient than ‘A’, if ‘C’ can do the work in 10 more days than ‘B’, find days taken by ‘A’ and ‘C’ together to complete the work?

  1. $\(\frac{1200}{49}\)$
  2. $\(\frac{600}{7}\)$
  3. $\(\frac{1250}{14}\)$
  4. $\(\frac{400}{49}\)$

  5. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A completes work in 48 days, so A's rate = 1/48. B is 20% more efficient, so B's rate = 1.2 × 1/48 = 1/40, meaning B completes in 40 days. C takes 10 more days than B, so C completes in 50 days (rate = 1/50). Combined rate of A and C = 1/48 + 1/50 = (50+48)/(48×50) = 98/2400 = 49/1200. Time = 1200/49 days. Option A is correct.

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