Pipes and Cistern


  1. Three pipes A, B and C can fill a tank in 30 min, 20 min and 10 min, respectively. When the tank is empty, all the three pipes are opened. If A, B and C discharge chemical solution P, Q and R respectively, then the part of solution R in the liquid in the tank after 3 min is ?









  1. View Hint View Answer Discuss in Forum

    Total quantity of solution P, Q and R from A, B and C receptively, after 3min
    = 3/30 + 3/20 + 3/10 = 3 x (2 + 3 + 6)/60 = 11/20

    Correct Option: C

    Total quantity of solution P, Q and R from A, B and C receptively, after 3min
    = 3/30 + 3/20 + 3/10 = 3 x (2 + 3 + 6)/60 = 11/20
    Quantity of solution R in liquid in 3 min = 3/10
    ∴ part of solution R = [3/10] / [11/20 ] = (3 x 20)/(10 x 11) = 6/11


  1. Two pipes A and B can fill a tank in 18 and 6 h, respectively. If both the pipes are opened simultaneously, how much time will be taken to fill the tank ?









  1. View Hint View Answer Discuss in Forum

    Part filled by A in 1 h = 1/18
    Part filled by B in by 1 h = 1/6
    Part filled (A + B) in 1 h =1/18 + 1/6 = (1 + 3)/18 = 4/18 = 2/9

    Correct Option: A

    Part filled by A in 1 h = 1/18
    Part filled by B in by 1 h = 1/6
    Part filled (A + B) in 1 h =1/18 + 1/6 = (1 + 3)/18 = 4/18 = 2/9
    Hence, both the pipes together will fill the tank in 9/2 h or 41/2 h



  1. Three taps A, B and C fill a tank in 20 min, 15 min and 12 min, respectively. If all the taps are opened simultaneously, how long will they take to fill 40% of the tank?









  1. View Hint View Answer Discuss in Forum

    Part of the tank filled in 1 min by A, B and C = 1/20 + 1/15 +1/12
    = (3 + 4 + 5)/60 = 12/60 = 1/5
    ∴ Time taken by A, B and C to fill the tank = 5 min

    Correct Option: B

    Part of the tank filled in 1 min by A, B and C = 1/20 + 1/15 +1/12
    = (3 + 4 + 5)/60 = 12/60 = 1/5
    ∴ Time taken by A, B and C to fill the tank = 5 min
    ∴ Time taken by A, B and C to fill 40% of the tank = 40% of 5 = (40/100) x 5 = 2 min.


  1. Capacity of tap B is 80% more than that of A. If both the taps are opened simultaneously, they take 45 h to fill the tank. How long will B take to fill the tank alone?









  1. View Hint View Answer Discuss in Forum

    Let time taken by B to fill the tank = T h.
    ∴ Time taken by A to fill the tank = T + (T x 80)/100 = 9T/5 h

    According to the formula,
    Time taken by both the taps to fill the tank = ab /(a + b)

    Correct Option: D

    Let time taken by B to fill the tank = T h.
    ∴ Time taken by A to fill the tank = T + (T x 80)/100 = 9T/5 h

    According to the formula,
    Time taken by both the taps to fill the tank = ab /(a + b)
    ⇒ 45 = (T x 9T/5)/(T + 9T/5)
    ⇒ 45 x 14T/5 = 9T2/5
    ∴ T = 45 x 14/9 = 70 h



  1. Taps A, B and C are attached with a tank and velocity of water coming through them are 42 L/h, 56 L/h and 48 L/h, respectively. A and B are inlets and C is outlet. If all the taps are opened simultaneously, tank is filled in 16 h. What is the capacity of the tank?









  1. View Hint View Answer Discuss in Forum

    Quantity of water admitted by tap A in 1 h = 42 L
    Quantity of water admitted by tap B in 1h = 56 L
    Quantity of water removed by tap C in 1 h = 48 L
    So, quantity of water filled in the tank in 1 h = ( 42 + 56 - 48 ) L = 50 L

    Correct Option: C

    Quantity of water admitted by tap A in 1 h = 42 L
    Quantity of water admitted by tap B in 1h = 56 L
    Quantity of water removed by tap C in 1 h = 48 L
    So, quantity of water filled in the tank in 1 h = ( 42 + 56 - 48 ) L = 50 L
    ∴ Quantity for water filled in 16 h = 16 x 50 = 800 L
    Hence, capacity of tank = 800 L