Multiple choice

Three person P,Q and R are assigned for a work. P and Q together can do it in 40 days, Q and R can do it in 36 days and all three together can do that work in 24 days. Then find in how many days Q alone can do the same work?

  1. 60

  2. 90

  3. 72

  4. 120
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Let P, Q, R be work rates per day. P + Q = 1/40, Q + R = 1/36, P + Q + R = 1/24. Subtracting first from third: R = 1/24 - 1/40 = 1/60. Then Q = 1/36 - 1/60 = 1/90. So Q alone takes 90 days. Options A, C, D are common miscalculations from incorrect subtraction.

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