Multiple choice

A, B and C all together can do a piece of work in 5 5/11 days. A takes 2 days less than the no of days taken by B and C together then find the no of days taken by A alone?

  1. 12

  2. 15

  3. 10

  4. 16

  5. 20
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let A take x days, B+C take x+2 days. Together they take 60/11 days. (1/x) + 1/(x+2) = 11/60. Solving this: (2x+2)/(x^2+2x) = 11/60 -> 120x + 120 = 11x^2 + 22x -> 11x^2 - 98x - 120 = 0. Roots are x = 10.

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