Multiple choice

X can do a piece of work in 25 days. Y is 25% more efficient than X. How many days does Y take to do the same piece of work?

  1. 15 days

  2. 20 days

  3. 21 days

  4. 18 days
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

If X takes 25 days, his efficiency is 1/25 work/day. Y is 25% more efficient, so Y's efficiency = 1.25 * (1/25) = (5/4) * (1/25) = 1/20 work/day. Thus, Y takes 20 days.

AI explanation

Using the efficiency method, if X takes 25 days to complete the work, X's efficiency is 4 units per day. Since Y is 25% more efficient, Y's efficiency is 5 units per day. The total work is 25 days times 4 units per day, which equals 100 units. Therefore, Y takes 100 units divided by 5 units per day, equaling 20 days.

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