Pipes and Cistern


  1. A cistern has two pipes. One can fill it with water in 8 hours and other can empty it in 5 hours. In how many hours will the cistern be emptied if both the pipes are opened together when 3/4 of the cistern is already full of water ?









  1. View Hint View Answer Discuss in Forum

    On the basis of given details in question ,

    Part of cistern emptied in 1 hour =
    1
    -
    1
    =
    8 - 5
    =
    3
    584040

    3
    part is emptied in 1 hour.
    40

    Correct Option: B

    On the basis of given details in question ,

    Part of cistern emptied in 1 hour =
    1
    -
    1
    =
    8 - 5
    =
    3
    584040

    3
    part is emptied in 1 hour.
    40

    3
    part is emptied in
    40
    ×
    3
    = 10 hours.
    434


  1. If 1/3 of a tank holds 80 litres of water, then the quantity of water that 1/2 tank holds is:









  1. View Hint View Answer Discuss in Forum

    Let the capacity of the tank be q litres , then
    According to question ,

    q
    = 80
    3

    ∴ q = 240

    Correct Option: B

    Let the capacity of the tank be q litres , then
    According to question ,

    q
    = 80
    3

    ∴ q = 240
    q
    =
    240
    = 120 litres
    22



  1. Pipe A can fill an empty tank in 6 hours and pipe B in 8 hours. If both the pipes are opened and after 2 hours pipe. A is closed, how much time B will take to fill the remaining tank?









  1. View Hint View Answer Discuss in Forum

    As per the given in question , we have

    Part of tank filled by pipes A and B in 2 hours = 2
    1
    +
    1
    68

    Part of tank filled by pipes A and B in 2 hours = 2
    4 + 3
    =
    7
    2412

    Remaining part = 1 –
    7
    =
    5
    1212

    This part is filled by pipe B.
    ∴ Required time =
    5
    × 8
    12

    Correct Option: D

    As per the given in question , we have

    Part of tank filled by pipes A and B in 2 hours = 2
    1
    +
    1
    68

    Part of tank filled by pipes A and B in 2 hours = 2
    4 + 3
    =
    7
    2412

    Remaining part = 1 –
    7
    =
    5
    1212

    This part is filled by pipe B.
    ∴ Required time =
    5
    × 8
    12

    Required time =
    10
    hours = 3
    1
    hours
    33


  1. A pipe can fill a tank in x hours and another can empty it in y hours. They can together fill it in (y > x)









  1. View Hint View Answer Discuss in Forum

    When both pipes are opened simultaneously,

    Part of the tank filled in 1 hour =
    1
    -
    1
    =
    y - x
    xyxy

    Correct Option: A

    When both pipes are opened simultaneously,

    Part of the tank filled in 1 hour =
    1
    -
    1
    =
    y - x
    xyxy

    ∴ Required time =
    xy
    hours
    y - x



  1. Two pipes A and B can separately fill a tank in 2 hours and 3 hours respectively. If both the pipes are opened simultaneously in the empty tank, then the tank will be filled in









  1. View Hint View Answer Discuss in Forum

    On the basis of given details in question ,

    Part of tank filled by pipes A and B in 1 hour =
    1
    +
    1
    =
    3 + 2
    =
    5
    part
    2366

    ∴ Required time =
    6
    hours
    5

    Correct Option: A

    On the basis of given details in question ,

    Part of tank filled by pipes A and B in 1 hour =
    1
    +
    1
    =
    3 + 2
    =
    5
    part
    2366

    ∴ Required time =
    6
    hours
    5

    Required time = 1 hour
    1
    × 60
    5

    Required time = 1 hour 12 minutes