Pipes and Cistern


  1. An inlet pipe fills 1/8 part of a tank in 1 h. How much time will the pipe take to fill the empty tank ?









  1. View Hint View Answer Discuss in Forum

    When a pipe fills 1/m part of a tank in 1 h, then the pipe takes m h to fill the tank.

    Correct Option: D

    We know that, when a pipe fills 1/m part of a tank in 1 h, then the pipe takes m h to fill the tank.
    Here, 1/m = 1/8 ⇒ m = 8
    ∴ Required time to fill the tank = 8 h


  1. An outlet pipe can empty a cistern in 3 h. In what time will the pipe empty two-third part of the cistern?









  1. View Hint View Answer Discuss in Forum

    Time taken by the pipe to empty the cistern = 3 h
    Then, time taken by the pipe to empty the 2/3 part = 3 x 2/3 = 2 h

    Correct Option: B

    Time taken by the pipe to empty the cistern = 3 h
    Then, time taken by the pipe to empty the 2/3 part = 3 x 2/3 = 2 h



  1. A pipe can fill a tank in 20 h. Due to a leak in the bottom, it is filled in 40 h. If the tank is full, how much time will the leak take to empty it ?









  1. View Hint View Answer Discuss in Forum

    Let the leak empties the full tank in x h, then
    Part emptied in 1 by leak = 1/x
    Part filled by inlet in 1 h = 1/20
    According to the question,
    1/20 + 1/x = 1/40

    Correct Option: A

    Let the leak empties the full tank in x h, then
    Part emptied in 1 by leak = 1/x
    Part filled by inlet in 1 h = 1/20
    According to the question,
    1/20 + 1/x = 1/40
    ∴ 1/x = 1/40 - 1/20 = 1- 2/40 = -1/40 [-ve sign Indicates emptying.]
    Clearly, leak will empty the full tank in 40 h.


  1. If a pipe fills a tank in 6 h, then what part of the tank will the pipe fill in 1 h ?









  1. View Hint View Answer Discuss in Forum

    We know that, when a pipe fills a tank in m h, then the part of tank filled in 1 h = 1/m

    Correct Option: B

    We know that, when a pipe fills a tank in m h, then the part of tank filled in 1 h = 1/m
    Here, m = 6
    ∴ Required part of the tank to be filled in 1 h = 1/6 part



  1. An outlet pipe can empty a cistern in 30 min, then what part of the cistern will it empty in 1 min ?









  1. View Hint View Answer Discuss in Forum

    We know that, when a pipe empties a cistern in n min, then the part emptied by the pipe in 1 min = 1/n

    Correct Option: C

    We know that, when a pipe empties a cistern in n min, then the part emptied by the pipe in 1 min = 1/n

    Here, n=30
    ∴ Required part of the tank emptied in 1 min = 1/30 part