Multiple choice

W and T together can do a work in 12 days. W alone can do the work in 15 days. In how many days can T alone do the work?

  1. 65 days

  2. 72 days

  3. 45 days

  4. 60 days
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

If W and T together do the work in 12 days, their combined rate is 1/12. W's rate is 1/15. T's rate is 1/12 - 1/15 = 5/60 - 4/60 = 1/60. Thus, T takes 60 days.

AI explanation

Let the total work be the least common multiple of 12 and 15, which is 60 units. The combined efficiency of W and T is 60 divided by 12, equaling 5 units per day. The individual efficiency of W is 60 divided by 15, equaling 4 units per day. T's individual efficiency is 5 minus 4, which equals 1 unit per day. Therefore, T alone will take 60 divided by 1 days to complete the work, resulting in 60 days.

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