Multiple choice

In two days, A, B and C together can finish 1/2 of a piece of work, and, in another two days B and C together can finish 3/10 part of the work. Then A alone can complete the whole work in

  1. 15 days

  2. 10 days

  3. 12 days

  4. 14 days

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

A+B+C in 2 days = 1/2, so in 1 day = 1/4. B+C in 2 days = 3/10, so in 1 day = 3/20. A's rate = 1/4 - 3/20 = 5/20 - 3/20 = 2/20 = 1/10. A takes 10 days to finish the work.

AI explanation

If A, B and C finish 1/2 of the work in two days, their combined rate is 1/4 of the work per day. Since B and C finish 3/10 of the work in two days, their combined rate is 3/20 of the work per day. Subtracting the rate of B and C from the combined rate of all three gives A's rate: 1/4 - 3/20 = 5/20 - 3/20 = 2/20 = 1/10 of the work per day. Therefore, A alone can complete the whole work in 10 days.

Keep practicing — related questions