Multiple choice

DIRECTION for the question: Solve the following question and mark the best possible option. X and Y can do a piece of work in 20 days and 12 days respectively. X started the work alone and then, after 4 days, Y joined him till the completion of the work. How long did the work last?

  1. 23

  2. 12

  3. 5

  4. 10

  5. 6
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

X does 1/20 of work per day, Y does 1/12. In 4 days, X does 4/20 = 1/5 of work. Remaining work = 4/5. Together, they do (1/20 + 1/12) = (3+5)/60 = 8/60 = 2/15 per day. Time for remaining work = (4/5) / (2/15) = (4/5) * (15/2) = 6 days. Total time = 4 + 6 = 10 days.

AI explanation

Using the Least Common Multiple method, let the total work be 60 units, making the daily work of X equal to 3 units and the daily work of Y equal to 5 units. In the first 4 days, X completes 12 units, leaving 48 units of work. When X and Y work together, their combined daily work is 8 units, so dividing the remaining 48 units by 8 gives 6 days, which means the work lasted 4 days plus 6 days. The result is 10 days.

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