Multiple choice

Time taken by A to do a piece of work is equal to time taken by B and C together to complete the same piece of work. A and B together can complete a work in 36 days and time taken by C to complete the work is 60 days. A and C started working together but, after 10 days both left the work, then find the time taken by B alone to complete the remaining work?

  1. 88 days

  2. 110 days

  3. 84 days

  4. 90 days
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Let total work = 180 units (LCM of 36 and 60). A + B = 5 units/day, C = 3 units/day. Given A = B + C, so A = B + 3. Substituting: (B + 3) + B = 5, B = 1 unit/day (90 days alone). A + C = (B + 3) + 3 = 7 units/day. In 10 days, A + C complete 70 units. Remaining 110 units at B's rate (1 unit/day) = 110 days. This matches option B.

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