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- Question
There is an empty reservoir whose capacity is 30 litres. There is an inlet pipe which fills at 5 L/min and there is an outlet pipe which empties at 4 L/min. Both the pipes function alternately for 1 minute. Assuming that the inlet pipe is the first one to function, how much time will it take for the reservoir to be filled up to its capacity?
Options- A. 49.5 min
- B. 50 min
- C. 51 min
- D. 52 min
- Correct Answer
- 51 min
ExplanationThe work to be done = Capacity of reservoir = 30 litres.
1st Minute ---> inlet pipe opened ---> 5 lit filled
2nd minute ---> inlet pipe closed; outlet pipe opened ---> 4 lit emptied
In 2 minutes (5 litres - 4 litres = 1lit) is filled into the reservoir.
It takes 2 minutes to fill 1lit ---> it takes 50 minutes to fill 25 litres into the reservoir.
In the 51st minute inlet pipe is opened and the reservoir is filled.
- 1. Two pipes can fill a tank in 20 and 24 minutes respectively and a waste pipe can empty 3 gallons per minute. All the three pipes working together can fill the tank in 15 minutes. The capacity of the tank is:
Options- A. 60 gallons
- B. 100 gallons
- C. 120 gallons
- D. 180 gallons Discuss
- 2. Two pipes A and B can separately fill a cistern in 10 and 15 minutes respectively. A person opens both the pipes together when the cistern should have been was full he finds the waste pipe open. He then closes the waste pipe and in another 3 minutes the cistern was full. In what time can the waste pipe empty the cistern when fill ?
Options- A. 8.21 min
- B. 8 min
- C. 8.57 min
- D. 8.49 min Discuss
- 3. A booster pump can be used for filling as well as for emptying a tank. The capacity of the tank is 2400 m3 . The emptying capacity of the tank is 10 m3 per minute higher than its filling capacity and the pump needs 8 minutes lesser to empty the tank than it needs to fill it. What is the filling capacity of the pump?
Options- A. 50 m^3/min
- B. 60 m^3/min
- C. 72 m^3/min
- D. None of these Discuss
- 4. A water tank is two-fifth full.Pipe A can fill a tank in 10 minutes and 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 min.to empty
- B. 6 min.to fill
- C. 9 min.to empty
- D. 9 min.to fill Discuss
- 5. A and B can fill the tank in 60 min and 90 min. There is a leak at 3/4th of the height. If leak is opened alone, it takes 36 min to empty till 3/4th the height. Find the time taken to fill the tank if all of the taps and the leak are opened simultaneously.
Options- A. 39
- B. 27
- C. 37
- D. 33 Discuss
- 6. Water flows into a tank which is 200 m long and 150 m wide, through a pipe of cross-section (0.3m x 0.2m) at 20 km/h. In what time will the water level be 12m ?
Options- A. 200 hrs
- B. 240 hrs
- C. 300 hrs
- D. 270 hrs Discuss
- 7. 12 buckets of water fill a tank when the capacity of each tank is 13.5 liters. How many buckets will be needed to fill the same tank,if the capacity of each bucket is 9 liters?
Options- A. 8
- B. 15
- C. 16
- D. 18 Discuss
- 8. One pipe can fill a tank three times as fast as another pipe. If together the two pipes can fill the tank in 36 min, then the slower alone will be able to fill the tank in:
Options- A. 81 min
- B. 108 min
- C. 144 min
- D. 192 min Discuss
- 9. Two pipes A and B can fill a tank in 16 hrs and 12 hrs respectively. The capacity of the tank is 240 liters. Both the pipes are opened simultaneously and closed after 2 hrs. How much more water need to fill the tank?
Options- A. 70 lit
- B. 170 lit
- C. 90 lit
- D. 190 lit Discuss
- 10. A large tanker can be filled by two pipes A and B in 60 and 40 minutes respectively. How many minutes will it take to fill the tanker from empty state if B is used for half the time and A and B fill it together for the other half ?
Options- A. 31 min
- B. 29 min
- C. 28 min
- D. 30 min Discuss
Pipes and Cistern problems
Search Results
Correct Answer: 120 gallons
Explanation:
Work done by the waste pipe in 1 minute = [-ve sign means emptying]
Volume of part = 3 gallons
Volume of whole = (3 x 40) gallons = 120 gallons.
Correct Answer: 8.57 min
Explanation:
1/10 + 1/15 = 1/6 x 3 = 1/2
1 - 1/2 = 1/2
1/10 + 1/15 - 1/x = 1/2
x = 8.57 min
Correct Answer: 50 m^3/min
Explanation:
Let the filling capacity of the pump be x /min.
Then, emptying capacity of the pump=(x+10) /min.
so,
Correct Answer: 6 min.to empty
Explanation:
Clearly,pipe B is faster than pipe A and so,the tank will be emptied.
part to be emptied = 2/5
part emptied by (A+B) in 1 minute=
so, the tank will be emptied in 6 min
Correct Answer: 39
Correct Answer: 300 hrs
Explanation:
Volume of water collected in the tank in 1 hour
? (0.3 × 0.2 × 20km × 1000mts) = 1200 m cubic
If after t hours, the water is at height of 12m,
1200t=200×150×12
? t = 300 Hours.
Correct Answer: 18
Explanation:
Capacity of the tank =(12 x 13.5) liters =162 liters.
Capacity of each bucket =9 liters
Number of buckets needed = 162/9 =18.
Correct Answer: 144 min
Explanation:
Let the slower pipe alone fill the tank in x minutes.
Then,faster pipe will fill it in x/3 minutes.
Correct Answer: 170 lit
Explanation:
Given A alone can fill the tank of capacity 240 lit in 16 hrs.
=> A can fill in 1 hr = 240/16 = 15 lit
=> B alone can fill the tank of capacity 240 lit in 12 hrs.
=> B can fill in 1 hr = 240/12 = 20 lit
Now, (A + B) in 1 hr = 15 + 20 = 35 lit
But they are opened for 2 hrs
=> 2 x 35 = 70 lit rae filled
Remaining water to be filled in tank of 240 lit = 240 - 70 = 170 lit.
Correct Answer: 30 min
Explanation:
Part filled by (A + B) in 1 minute = (1/60 + 1/40) = 1/24
Suppose the tank is filled in x minutes.
Then, x/2(1/24 + 1/40) = 1
(x/2) * (1/15) = 1 => x = 30 min.
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