Question
P alone can finish a piece of work ‘M’ in 6
days while Q takes 3 days to finish it alone. P, Q and R working together can finish the work ‘N’ which is 10 times of work ‘M’ in 4 days. How long will R take to finish work ‘N’, when working alone? Let the work ‘M’ = 6 units (LCM of 6 and 3)Solution
Efficiency of P = 6/6 = 1 units Efficiency of Q = 6/3 = 2 units Efficiency of P, Q and R = (6 × 10)/4 = 15 units per day Efficiency of R = 15 – (1 + 2) = 12 units per day Time taken by R to finish work ‘N’ = 60/12 = 5 days
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