Quantitative Aptitude :: Pipes & Cistern - Discussion

Show Explanation

Please attempt the question to view the Explanation !!!

Explanation:
Tank filled by (A+B) in 1 hour = (1/12+1/15) = 9/60 = 3/20
Tank filled by (A+C) in 1 hour = (1/12+1/20) = 8/60 = 2/15
So tank filled in 2 hours = (3/20 + 2/15) = 17/60
Tank part filled in 6 hrs = 3*17/60 = 17/20

Remaining part = (1-17/20) = 3/20

Now, it is the turn of A and B (3/20) part is filled by A and B in 1 hour.
So Total time taken to fill the tank =(6+1)hrs= 7 hrs