Multiple choice

X can do a piece of work in 15 days. If he is joined by Y, who is 50% more efficient, in what time will X and Y together finish the work?

  1. 10 days

  2. 6 days

  3. 18 days

  4. Data insufficient

  5. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

X's efficiency = 1 unit/day. Y is 50% more efficient, so Y's efficiency = 1.5 units/day. Combined efficiency = 2.5 units/day. Total work = 15 days * 1 unit/day = 15 units. Time taken = 15 / 2.5 = 6 days.

AI explanation

Let X's efficiency be 2 units per day, so Y's efficiency is 3 units per day. The total work is 2 units per day times 15 days, which equals 30 units. Working together, their combined efficiency is 5 units per day. The time required is 30 units divided by 5 units per day, which equals 6 days.

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