P can lay railway track between two stations in 16 days. Q can do the same job in 12 days. With the help of R, they completes the job in 4 days. How much days does it take for R alone to complete the work?
Q1. P can lay railway track between two stations in 16 days. Q can do the same job in 12 days. With the help of R, they completes the job in 4 days. How much days does it take for R alone to complete the work?
Answer: 9(3/5) days
Explanation: 1/P+1/Q+1/R = 1/4; 1/16+1/12+1/R = 1/4 → 1/R = 5/48; R alone takes 48/5 = 9⅗ days.