Multiple choice

A and B together can complete a work in $4$ days. A alone can finish the work in $12$ days, In how many days B alone can finish the work?

  1. $5$
  2. $15$
  3. $6$
  4. $8$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

If A and B together take 4 days, their combined rate is 1/4 of the work per day. Since A alone takes 12 days, his rate is 1/12. B's rate is 1/4 - 1/12 = 3/12 - 1/12 = 2/12 = 1/6. Thus, B takes 6 days.

AI explanation

Using the formula for combined work, B's 1 day work is 1/4 minus 1/12, which equals 1/6. Therefore, B alone can finish the work in the reciprocal of 1/6 days, resulting in 6 days.

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