Question
Ravi and Sita together can complete a piece of work in
150 days and 3 minutes, while Sita and Ramesh together can complete the same work in 90 days and 2.5 minutes. If the efficiency of Ramesh is 39.98% less than that of Sita, then find the approximate time taken by all three of them to complete 75% of the work together.Solution
ATQ Let the efficiency of Sita be '2y' units/day. So, the efficiency of Ramesh = 0.60 × 2y = '1.2y' units/day. So, total work = (2y + 1.2y) × 90 = '288y' units. So, combined efficiency of Ravi and Sita = (288y/150) = '1.92y' units/day. Therefore, required time = [(288y × 0.75) ÷ (2y + 1.2y)] = 60 days.
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