Multiple choice

P, Q and R together can complete a work in 20 days. If P alone can complete the work in 40 days and Q alone in 60 days, then in how many days can R alone complete the work?

  1. 60 days

  2. 80 days

  3. 40 days

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

Rates: P+Q+R = 1/20, P = 1/40, Q = 1/60. R = 1/20 - 1/40 - 1/60 = (6-3-2)/120 = 1/120. R takes 120 days.

AI explanation

The combined one day work of P, Q, and R is 1/20. P's one day work is 1/40 and Q's one day work is 1/60, so their combined work is 1/24. Subtracting 1/24 from 1/20 gives R's one day work as 1/120, which means R alone can complete the work in 120 days.

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