Key Concepts: Pipes and Cisterns
1. Inlet: A pipe used to fill the tank, cistern, or reservoir is known as an 'Inlet'. This indicates 'plus' or 'positive' work done.
2. Outlet: A pipe used to empty the tank, cistern, or reservoir is known as an 'Outlet'. This indicates 'minus' or 'negative' work done.
Net Work Done = (Sum of work done by inlets) - (Sum of work done by outlets)
💡 Pro Tip by Wisdom Helps Maths:
- If a pipe fills a tank in x hours, its 1-hour work = 1/x
- Always use the LCM Method to find the Total Capacity of the tank for faster calculations.
- If the Net Work is Positive, the tank is filling; if Negative, the tank is emptying.
Pipes and Cisterns: Practice Set
Boost your Aptitude and Reasoning skills
1. Two pipes A & B can fill a tank in 12 hours and 36 hours respectively. If both are opened simultaneously, how much time is required to fill the tank?
2. Two pipes can fill a tank in 6h and 8h respectively, while a third pipe empties the full tank in 12h. If all three operate together, in how much time will the tank be filled?
3. A cistern is normally filled in 8 hours but takes two hours longer because of a leak in its bottom. If full, how long will the leak take to empty it?
4. A cistern can be filled by pipe A in 6 hrs and emptied by pipe B in 12 hrs. If opened alternately starting with A, in how many hours will it be full?
5. Two taps A and B fill a tank in 40 mins and 60 mins. If opened at 5 am, at what time should A be closed so the tank is full in 36 mins?
6. 12 pumps working 6 hours a day can empty a reservoir in 15 days. How many pumps working 9 hours a day will empty it in 12 days?
7. A tank is filled in 45 minutes by two pipes, A and B. Pipe B fills the tank twice as fast as A. How much time (in minutes) will pipe A alone take to fill the tank?
8. Pipe A can fill an empty tank in 6 hours and pipe B in 8 hours. If both are opened and after 2 hours pipe A is closed, how much time will B take to fill the remaining tank?
9. A cistern has two pipes. One can fill it in 8 hours and the other can empty it in 5 hours. In how many hours will the cistern be emptied if both are opened together when 3/4 of the cistern is already full?