**Q1. Three pipes A, B and C can fill a tank in 15 minutes, 20 minutes and 30 minutes respectively. The pipe C is closed 6 minutes before the tank is filled. In what time the tank will be full?**

**Q2. One filling pipe A is 5 times faster than second filling pipe B. If B can fill a cistern in 36 minutes, the find the time when the cistern will be full if both fill pipes are opened together.**

**Q3. Pipe A can fill an empty tank in 30 hours while B can fill it in 45 hours. Pipe A and B are opened and closed alternatively i.e., first pipe A is opened, then B, again A and then B and so on for 1 hour each time without any time lapse. In how many hours the tank will be filled if it was empty, initially?**

**Q4. A cistern can be filled by two taps A and B coming from the same main pipeline in 20 and 30 minutes respectively. Both the taps are opened at the same time but due to partial closing of a valve in the main pipeline, tap A was supplying only 4/5th of its capacity and tap B, 5/6th of its capacity. After some time, the valve in the main pipeline was opened fully thereby enabling the two taps to supply at full capacity. It took another 5 minutes to fill the cistern completely. How long (approx) was it before the valve on the main pipeline opened?**

**Q5. A tank has three pipes. The first pipe can fill 1/2part of the tank in 1 hour and the second pipe can fill 1/3 part in 1 hour. The third pipe is for making the tank empty. When all the three pipes are open, 7/12th part of the tank is filled in 1 hours. How much time will the third pipe take to empty the completely filled tank?**

**Q6. Two taps can separately fill a tank in 12 min and 15 min. The first tap was replaced with a tap of double the radius and the second tap was replaced with a tap of half the radius. Now in what time will the tank get filled?**

**Q7. A bath can be filled by the cold water pipe in 20 minutes and by the hot water pipe in 30 minutes. A person leaves the bathroom after turning on both pipes simultaneously and returns at the moment when the bath should be full. Finding, however, that the waste pipe has been open, he now closes it. In 6 minutes more the bath is full. In what time would the waste pipe empty it?**

**Q8. A water tank can be filled by a tap in 30 minutes and another tap can fill it in 60 minutes. If both the taps are kept open for 5 minutes and then the first tap is closed, how long will it take for the tap to fill the remaining part of the tank?**

**Q9. Pipe A can fill a tank in 36 minutes and pipe B can fill it in 45 minutes. If both the pipes are opened to fill an empty tank, in how many minutes will it be full?**

**Q10. Tap A can fill the empty tank in 12 hours, but due to a leak in the bottom it is filled in 15 hours. If the tank is full and then tap A is closed then in how many hours the leak can empty it?**

**Q11. Pipe A and Pipe B can fill a cistern in 10 hours and 15 hours respectively. When a third pipe C which works as an outlet pipe is also open then the cistern can be filled in 18 hours. The outlet pipe can empty a full cistern in:**

**Q12. A cistern has a leak which would empty it in 6 hours. A tap is turned on which fills the cistern @ 10 liters per hour and when the tank is full then it is emptied in 15 hours(when tap and the leak are active). What is the capacity of the cistern?**

**Q13. Tap A fills a tank in 10 hours and B can fill it in 15 hours. Both are opened simultaneously. Sometimes later tap B was closed, then it takes total 8 hours to fill up the whole tank.**

**After how many hours B was closed?**

**Q14. Tap A can fill a tank in 20 hours, B in 25 hours but tap C can empty a full tank in 30 hours. Starting with A, followed by B and C each tap opens alternatively for one hour period till the tank gets filled up completely. In how many hour the tank will be filled up completely?**

**Q15. If one pipe A can fill a tank in 20 minutes, then 5 pipes, each of 20% efficiency of A, can fill the tank in:**