Multiple choice

A and B together can finish a piece of work in 7.5 days. A alone can finish the work in 30 days. How long will B take to finish the work alone?

  1. 10 days

  2. 6 days

  3. 15 days

  4. 22.5 days

  5. -
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A+B = 1/7.5 = 2/15. A = 1/30. B = 2/15 - 1/30 = 4/30 - 1/30 = 3/30 = 1/10. B takes 10 days.

AI explanation

Using the formula for combined work, (A and B)'s one day work = 1/7.5 and A's one day work = 1/30. B's one day work is calculated as 1/7.5 minus 1/30, which equals 2/15 minus 1/30. This simplifies to 4/30 minus 1/30, resulting in 3/30 or 1/10. Therefore, B alone takes the reciprocal of 1/10, which is 10 days, to finish the work.

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