Pipes and cisterns
- Pipe A can fill a tank in 12 minutes and pipe B in 15 minutes, while pipe C can empty the full tank in 20 minutes. If all three are opened together on an empty tank, in how much time will the tank be filled? Answer: C. 10 minutes Answer: (C) 10 minutes Net part filled per minute = 1/12 + 1/15 - 1/20 = 5 + 4 - 3/60 = 1/10 . So the tank fills in 10... 1
- A pipe can fill a tank in 8 hours. Because of a leak at the bottom, it takes 10 hours to fill the tank. In how many hours can the leak alone empty the full tank? Answer: B. 40 Answer: (B) 40 Leak rate = 1/8 - frac110 = 1/40 . The leak empties the tank in 40 hours. 1
- Pipes A and B can fill a tank in 20 minutes and 30 minutes respectively, and pipe C can empty the full tank in 15 minutes. If all three pipes are opened together on an empty tank, in how many minutes will it be filled? Answer: D. 60 Answer: (D) 60 Net rate = 1/20+1/30-1/15 = 3+2-4/60 = 1/60 . Time = 60 minutes. 1
- Pipes A and B can fill a tank in 20 minutes and 30 minutes respectively, and pipe C can empty it in 15 minutes. If all three are opened together, in how much time will the empty tank be filled? Answer: A. 60 minutes Answer: (A) 60 minutes Net rate = 1/20 + 1/30 - 1/15 = 3 + 2 - 4/60 = 1/60 . Time = 60 minutes. 1