Question

TYPE 25

P alone can finish a piece of work ‘M’ in 12 days while Q takes 8 days to finish it alone. P, Q and R working together can finish the work ‘N’ which is 10 times of work ‘M’ in 12 days. How long will R take to finish work ‘N’, when working alone?

A 16 days Correct Answer Incorrect Answer
B 15 days Correct Answer Incorrect Answer
C 13.5 days Correct Answer Incorrect Answer
D 12 days Correct Answer Incorrect Answer
E 14 days Correct Answer Incorrect Answer

Solution

 Let the work ‘M’ = 24 units (LCM of 12 and 8) Efficiency of P = 24/12 = 2 units Efficiency of Q = 24/8 = 3 units Efficiency of P, Q and R = (24 × 10)/12 = 20 units per day Efficiency of R = 20 – (2 + 3) = 15 units per day Time taken by R to finish work ‘N’ = 240/15 = 16 days

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