Multiple choice

P, Q and R take (x - 28) days, (x - 18) days and (x - 8) days respectively to complete a job. The three work in a rotation to complete the job with only 1 person working on a day. Who should start the job so that the job is completed in the least possible time?

  1. P

  2. Q

  3. R

  4. Any one of the three

  5. Cannot be determined
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A Correct answer
Explanation

P, Q, R take x-28, x-18, x-8 days. Their rates are 1/(x-28), 1/(x-18), 1/(x-8). To finish in the least time, the person with the highest rate (shortest time) should start. Since x-28 < x-18 < x-8, P is the fastest.

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