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Home Aptitude Pipes and Cistern Comments

  • Question
  • Three taps A,B and C can fill a tank in 12,15 and 20 hours respectively. If A is open all the time and B ,C are open for one hour each alternatively, the tank will be full in:


  • Options
  • A. 6 hrs
  • B. 20/3 hrs
  • C. 7 hrs
  • D. 15/2 hrs

  • Correct Answer
  • 7 hrs 

    Explanation

    A + B ' s   1   h o u r   w o r k = 1 12 + 1 15 = 9 60 = 3 20

    A + C ' s   1   h o u r   w o r k = 1 12 + 1 20 = 8 60 = 2 15   

     

    p a r t   f i l l e d   i n   2   h r s = 3 20 + 2 15 = 17 60   

     

    p a r t   f i l l e d   i n   6   h r s = 3 * 17 60 = 17 20   

     

      r e m a i n i n g   p a r t   = 1 - 17 20 = 3 20   

     

    Now, it is  the turn of A and B (3/20) part is filled by A and B in 1 hour.

    Therefore, Total  time taken to fill the tank =(6+1)hrs= 7 hrs


  • Pipes and Cistern problems


    Search Results


    • 1. Three pipes A, B and C can fill a tank in 6 hours. After working at it together for 2 hours, C is closed and A and B can fill the remaining part in 7 hours. The number of hours taken by C alone to fill the tank is:

    • Options
    • A. 10
    • B. 12
    • C. 14
    • D. 16
    • Discuss
    • 2. A tap can fill a tank in 6 hours. After half the tank is filled, three more similar taps are opened. What is the total time taken to fill the tank completely?

    • Options
    • A. 3 hrs 15 min
    • B. 3 hrs 45 min
    • C. 4 hrs 15 min
    • D. 4 hrs 1
    • Discuss
    • 3. A pump can fill a tank with water in 2 hours. Because of a leak, it took 213 hours to fill the tank. The leak can drain all the water of the tank in:

    • Options
    • A. 7 hours
    • B. 8 hours
    • C. 12 hours
    • D. 14 hours
    • Discuss
    • 4. Two pipes A and B can fill a tank in 15 minutes and 20 minutes respectively. Both the pipes are opened together but after 4 minutes, pipe A is turned off. What is the total time required to fill the tank?

    • Options
    • A. 10 min. 20 sec.
    • B. 11 min. 45 sec.
    • C. 12 min. 30 sec.
    • D. 14 min. 40 sec.
    • Discuss
    • 5. 16 persons are participated in a party. In how many differentways can they host the seat in a circular table, if the 2particular persons are to be seated on either side of the host?

    • Options
    • A. 16! × 2
    • B. 14! × 2
    • C. 18! × 2
    • D. 14!
    • Discuss
    • 6. A cistern is normally filled in 8 hours but takes two hours longer to fill because of a leak in its bottom. If the cistern is full, the leak will empty it in ?

    • Options
    • A. 20 hrs
    • B. 28 hrs
    • C. 36 hrs
    • D. 40 hrs
    • Discuss
    • 7. 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
    • 8. 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
    • 9. 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
    • 10. 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


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