Multiple choice

A and B separately can complete a piece of work in 10 and 15 days, respectively. A worked for 4 days alone and B worked for 5 days alone. Then, C completed the remaining portion of the work alone in 8 days. How long would all the three take together to complete the work?

  1. 4 days

  2. 5 days

  3. 6 days

  4. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
AI explanation

Using the Least Common Multiple method, assume the total work is 30 units. The daily work capacities of A and B are 3 units and 2 units, respectively. A completes 12 units in 4 days, and B completes 10 units in 5 days, leaving 8 units of work, which C completes in 8 days, giving C a capacity of 1 unit per day. The combined daily capacity of A, B, and C is 6 units (3 + 2 + 1), so they will complete the 30 units of work in 5 days.

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