Multiple choice

A, B and C can do a work in 36 days, 52 days and 72 days respectively. All the three began the work together but A left 8 days and B left 12 days before the completion of work. How many days in all did C put in till the entire work was finished?

  1. 18 days

  2. 20 days

  3. 24 days

  4. 28 days

  5. 30 days
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let total work be LCM(36,52,72)=468 units. A's rate=13, B's rate=9, C's rate=6.5 units/day. If total time is x days, A worked x-8 days, B worked x-12 days, C worked x days. 13(x-8)+9(x-12)+6.5x=468. Solving: 28.5x-232=468, x=24. C worked all 24 days.

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