Multiple choice

A and B can do a job in 6 and 12, respectively. They began the work together but A leaves after 3 days. Then the total number of days needed for the completion of the work is -

  1. 4

  2. 6

  3. 5

  4. 9
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A's 1-day work = 1/6, B's 1-day work = 1/12. Together in 3 days: 3(1/6 + 1/12) = 3(3/12) = 9/12 = 3/4 work done. Remaining 1/4 work by B alone: (1/4)/(1/12) = 3 days. Total = 3 + 3 = 6 days.

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