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- Question
- Two pipes X and Y can fill a cistern in 24 min. and 32 min. respectively. If both the pipes are opened together, then after how much time Y should be closed so that the tank is full in 18 minutes?
Options- A. 6 min.
- B. 8 min.
- C. 10 min.
- D. 12 min.
- Correct Answer
- 8 min.
ExplanationLet Y be closed after T min
Then, T x (1/ 24 + 1/32) + (18 - T) x 1/24 = 1
? (7 x T)/96 + (18 - T)/24 = 1
or 7T + 72 - 4T = 96.
? 3T = 24
or T = 8 min. - 1. A leak in the bottom of a tank can empty the full tank in 6 hours. An Inlet pipe fills water at the rate of 4 litres per minute. When the tank is full, the Inlet is opened and due to the leak the tank is empty in 8 hours. The capacity of the tank is?
Options- A. 5260 litres
- B. 5760 litres
- C. 5846 litres
- D. 6970 litres Discuss
- 2. A pipe can fill a cistern in 12 minutes and another pipe can fill it in 15 minutes, but a third pipe can empty it in 6 minutes. The first two pipes are kept open for 5 minutes in the beginning and then third pipe is also opened. In what time is the cistern emptied?
Options- A. 30 min.
- B. 33 min.
- C. 371 / 2 min.
- D. 45 min. Discuss
- 3. Three pipes A, B and C can fill a cistern in 10 hours, 12 hours and 15 hours respectively. First A was opened. After 1 hour, B was opened and after 2 hours from the start of A, C also opened . Find the time in which the cistern is just full?
Options- A. 2 hrs.
- B. 4 hrs.
- C. 2 hrs. 52 min.
- D. 4 hrs. 52 min. Discuss
- 4. Two pipes, P ans Q can fill a cistern in 12 and 15 minutes respectively. Both are opened together, but at the end of 3 minutes the first is turned off. How much longer will the cistern take to fill?
Options- A. 81/4 minutes
- B. 11 1/4 minutes
- C. 73/4 minutes
- D. 83/4 minutes Discuss
- 5. A cistern has 3 pipes A, B and C, A and B can fill it in 2 and 3 hours respectively. C is a waste pipe. If all the 3 pipes be opened at once, 7/24 of the cistern will be filled up in 30 minutes. In what time can C empty the full cistern?
Options- A. 3 hours
- B. 4 hours
- C. 5 hours
- D. 6 hours Discuss
- 6. A water tank is 2/5th full pipe A can fill the tank in 10 minutes and the pipe B can empty it in 6 minutes. If both the pipes are open, how long will it take to empty or fill the tank completely?
Options- A. 6 minutes to empty
- B. 6 minutes to fill
- C. 9 minutes to empty
- D. 9 minutes to fill Discuss
- 7. Top A can fill a water tank in 25 minutes, tap B can fill the same tank in 40 minutes and tap C can empty the tank in 30 minutes. If all the three taps are opened together, in how many minutes will the tank be completely filled up or emptied?
Options- A. 32/13
- B. 155/13
- C. 82/13
- D. 3111/19 Discuss
- 8. A cistern can be filled by two pipes. A and B in 12 minutes and 14 minutes respectively and can be emptied by a third pipe C in 8 minutes. If all the taps be turned on at the same moment, what part of cistern will remain unfilled at the end of 7 minutes?
Options- A. 5/24
- B. 19/24
- C. 7/24
- D. 17/24 Discuss
- 9. A cistern can be filled by two pipes in 30 and 40 minutes respectively. Both the pipes were opened at once, but after some time the first was shut up and the cistern was filled in 10 minutes more. How long after the pipes had opened was the first pipe shut up?
Options- A. 90/ 11 minutes
- B. 90/7 minutes
- C. 90/13 minutes
- D. 45/2 minute Discuss
- 10. A cistern has a leak which would empty it in 15 hours. A tap is turned on which admits 2 litres per hour into the cistern and it is now emptied in 10 hours. How many litres does the cistern hold?
Options- A. 50 litres
- B. 60 litres
- C. 45 litres
- D. 360 litres Discuss
Pipes and Cistern problems
Search Results
Correct Answer: 5760 litres
Explanation:
Part filled by inlet in 1 hour = (1/6 - 1/8) = 1/24
So, the inlet can fill the tank in 24 hours
? Capacity of the tank = Water that flows in 24 hours = (4 x 24 x 60) liters = 5760 liters
Correct Answer: 45 min.
Explanation:
Part filled in 5 min. = 5 x (1/12 + 1/15) = 5 x 9/60 = 3/4
Part emptied in 1 min. (when all the pipes are opened) = 1/6 - (1/12 + 1/15) = (1/6 - 3/20) = 1/60
Now, 1/60 part is emptied in 1 min. 3/4 part will be emptied in (60 x 3/4) = 45 min.
Correct Answer: 4 hrs. 52 min.
Explanation:
[(A's 1 hour work) + (A + B)'s 1 hour work]
= (1/10) + [(1/10) + (1/12)] = 17/60
Remaining part = 1 - (17/60) = 43/60
Now, (A + B + C)'s 1 hour work = (1/10) + (1/12) + (1/15) = 1/4
1/4 part is filled by 3 pipes in 1 hour.
43/60 part will be filled by them in 4 x (43/60) hrs. = 2 hours 52 min.
? Total time taken to fill the cistern = 4 hours 52 min.
Correct Answer: 81/4 minutes
Explanation:
12(1 - t/25) = 3
? t = 45/4 = 111/4 minutes
? Required answer = 111/4 - 3
= 81/4 minutes
Correct Answer: 4 hours
Explanation:
? 7/24 of the cistern will be filled up in 1/2 hr.
? The whole of the cistern will be filled up in (1/2) x (24/7) = 12/7 hrs.
Let the pipe C be empty the whole cistern in h hours
Now, applying the given rule we have,
(2 x 3 x h) / (3 x h + 2 x h - 2 x 3) = 12/7
or 42h = 60h - 72
? h = 4 hours.
Correct Answer: 6 minutes to empty
Explanation:
Time taken to fill or empty the whole tank = (6 x 10) /(6 - 10) = - 15 minutes
- ve sign shows that the tank will be emptied.
? 2/5th full of the tank will be emptied in 15 x 2/5 = 6 minutes
Correct Answer: 3111/19
Explanation:
Required answer = (25 x 40 x 30) / (40 x 30 + 25 x 30 - 25 x 40)
= 600 / 19 = 3111/19 minutes
Correct Answer: 19/24
Explanation:
Time taken to fill the whole tank = (12 x 14 x 8) / (14 x 8 + 12 x 8 - 12 x 14) = 168/5 minutes
? In 7 minutes 5/168 x 7 = 5/24 part of the tank will be filled
? Requied answer = 1 - 5/24 = 19/24 part
Correct Answer: 90/7 minutes
Explanation:
Let the first pipe be shut up after x minutes
Now, applying the given rule, we have 30{1 - (x + 10)/40 } = x
[Here t = (x + 10) minutes]
or x = 90/7 minutes
Correct Answer: 60 litres
Explanation:
Here w = 2 litres per hour
? Required answer = {(15 x 10) / (15 - 10)} x 2 = 60 litres.
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