Delhi Police Constable Exam Model Paper 6

Given:
Ram alone can complete a work in 20 days
Shyam alone can complete a work in 15 days
Formula: Total work = Efficiency × Time
Calculation:
Total work = 60 units (LCM of 20 and 15)
Efficiency of Ram = 3 units/day
Efficiency of Shyam = 4 units/day
Work done by Ram in 3 days = 3 × 3 = 9 units
Remaining work = 60 – 9 = 51 units
∴ Time taken by Ram and Shyam remaining work = 51/(3 + 4) = 51/7 days