Multiple choice

P and Q can do a piece of work in 14 days. Q and R together can do it in 21 days. If P is twice as good a workman as R, then in how many days Q alone can do the work?

  1. 42 days

  2. 40 days

  3. 35 days

  4. 38 days
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Let total work be LCM(14,21)=42 units. P+Q do 3 units/day and Q+R do 2 units/day. Since P is twice as efficient as R, let R=1 unit/day, then P=2 units/day. From Q+R=2, we get Q=1 unit/day. Q alone takes 42/1=42 days.

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