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Aptitude Questions – Pipes & Cistern Set 11

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Hello Aspirants. Welcome to Online Quantitative Aptitude Section with explanation in AffairsCloud.com. Here we are creating question sample in Pipes & Cistern which is common for all competitive exams. We have included Some questions that are repeatedly asked in bank exams !!!

  1. A Special pump can be used for filling as well as for emptying a Cistern. The capacity of the Cistern is 2400m³. The emptying capacity of the Cistern is 10m³ per minute higher than its filling capacity and the pump needs 8 minutes lesser to Cistern the tank than it needs to fill it. What is the filling capacity of the pump?
    A. 40m³/min
    B. 50m³/min
    C. 60m³/min
    D. 30m³/min
    E. None of the Above
    Answer – B. 50m³/min
    Explanation :
    Filling Capacity of the Pump = x m/min
    Emptying Capacity of the pump = (x+10) m/min
    2400/x – 2400/x+10 = 8
    (x – 50) + (x + 60) = 0
    x = 50

  2. Three pipes P, Q and R can fill a Cistern in 6 hours. After working at it together for 2 hours, R is closed and P and Q can fill the remaining part in 7 hours. The number of hours taken by R alone to fill the Cistern is
    A. 14 hours
    B. 12 hours
    C. 15 hours
    D. 18 hours
    E. None of the Above
    Answer – A. 14 hours
    Explanation :
    Part filled in 2 hours = 2/6 = 1/3
    Remaining Part = (1-1/3) = 2/3
    (P + Q)’s 7 hour work = 2/3
    (P + Q)’s 1 hour work = 2/21
    R’s 1 hour work = (P + Q + R) 1 hour work – (P + Q) 1 hour work
    = (1/6 – 2/21) = 1/14 = 14 hours

  3. A Cistern 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?
    A. 5 minutes
    B. 4 minutes
    C. 6 minutes
    D. 8 minutes
    E. None of the Above
    Answer – C. 6 minutes
    Explanation :
    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= (1/6 – 1/10) = 1/15
    1/15 : 2/5 :: 1: x
    2/5 * 15 = 6 minutes.

  4. If a pipe A can fill a tank 3 times faster than pipe B. If both the pipes can fill the tank in 32 minutes, then the slower pipe alone will be able to fill the tank in?
    A. 128 minutes
    B. 124 minutes
    C. 154 minutes
    D. 168 minutes
    E. None of the Above
    Answer – A. 128 minutes
    Explanation :
    Time is taken by pipe A = x
    Time is taken by pipe B = x/3
    1/x + 3/x = 1/32
    x = 128 minutes

  5. A large cistern can be filled by two pipes P and Q in 15 minutes and 20 minutes respectively. How many minutes will it take to fill the Cistern from an empty state if Q is used for half the time and P and Q fill it together for the other half?
    A. 12 minutes
    B. 17 minutes
    C. 18 minutes
    D. 19 minutes
    E. None of the Above
    Answer – A. 12 minutes
    Explanation :
    Part filled by P and Q = 1/15 + 1/20 = 7/60
    Part filled by Q = 1/20
    x/2(7/60 + 1/20) = 12 minutes

  6. A pipe can fill a cistern in 16 hours. After half the tank is filled, three more similar taps are opened. What is the total time taken to fill the cistern completely?
    A. 3 hours
    B. 2 hours
    C. 9 hours
    D. 4 hours
    E. None of the Above
    Answer – C. 9 hours
    Explanation :
    In One hour pipe can fill = 1/16
    Time is taken to fill half of the tank = 1/2 * 16 = 8 hours
    Part filled by four pipes in one hour = (8*1/16) = 1/2
    Required Remaining Part = 1/2
    Total time = 8 + 1 = 9

  7. Two pipes P and Q are opened together to fill a tank. Both the pipes fill the tank in time “x” If Q separately took 25 minutes more time than “x” to fill the tank and Q took 49 minutes more time than “x” to fill the tank, then find out the value of x?
    A. 48 minutes
    B. 35 minutes
    C. 54 minutes
    D. 68 minutes
    E. None of the Above
    Answer – B. 35 minutes
    Explanation :
    Time is taken to fill the tank by both Pipes x = √a*b
    x = √25*49 = 5 * 7 = 35

  8. Three taps P, Q and R can fill a tank in 12, 15 and 20 hours respectively. If P is open all the time and Q, R are open for one hour each alternatively, the tank will be full in
    A. 3 hours
    B. 2 hours
    C. 7 hours
    D. 4 hours
    E. None of the Above
    Answer – C. 7 hours
    Explanation :
    (P + Q)’s 1 hour work = 1/12 + 1/15 = 3/20
    (P + R)’s 1 hour work = 1/12 + 1/20 = 2/15
    For 2 hrs = (3/20 + 2/15) = 17/60
    For 6 hrs = (3*17/60) = 17/20
    Remaining Part = 1 – 17/20 = 3/20 filled by P and Q in 1 hour

  9. Pipe A fills a tank in 30 minutes. Pipe B can fill the same tank 5 times as fast as pipe A. If both the pipes were kept open when the tank is empty, how much time will it take for the tank to overflow?
    A. 3 minutes
    B. 2 minutes
    C. 5 minutes
    D. 4 minutes
    E. None of the Above
    Answer – C. 5 minutes
    Explanation :
    Total Capacity = 90L.
    Tank filled in 1 minute by A = 3L
    Tank filled in 1 minute by B = 15L
    The capacity of the tank filled with both A and B in 1 minute = 18L.
    overflow = 90/18 = 5 minutes.

  10. Two pipes P and Q can fill a cistern in 10 hours and 20 hours respectively. If they are opened simultaneously. Sometimes later, tap Q was closed, then it takes total 5 hours to fill up the whole tank. After how many hours Q was closed?
    A. 14 hours
    B. 15 hours
    C. 10 hours
    D. 16 hours
    E. None of the Above
    Answer – C. 10 hours
    Explanation :
    Pipe P Efficiency = 100/10 = 10%
    Pipe Q Efficiency = 100/20 = 5%
    Net Efficiency = 15%
    15x + 10(5-x) = 100
    x = 10