Two pipes A and B can fill a tank in 60 minutes and 75 minutes respectively

Two pipes A and B can fill a tank in 60 minutes and 75 minutes respectively. There is also an outlet C. If A, B and C are opened together, the tank is full in 50 minutes. How much time will be taken by C to empty the full tank?
(a) 100 minutes
(b) 110 minutes
(c) 120 minutes
(d) 125 minutes

Anurag Mishra Professor Asked on 19th February 2016 in Maths.
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  • 1 Answer(s)

    Answer: (a) 100 minutes

    Solution:-
    A pipe can fill a tank = 60 minutes
    Therefore, A pipe can fill a tank in minute = 1/60

    B pipe can fill a tank = 75 minutes 
    Therefore, B pipe can fill a tank in a minute = 1/75

    A, B and C together can fill a tank = 50 minutes
    Therefore, A, B and C can fill a tank in a minute = 1/50

    Thus, C pipe can empty a tank in minute = 1/50 – (1/60 + 1/75)
     = {6 – (5 + 4)}/300
     = -3/300
     = 1/100

    Therefore, C pipe can empty same tank = 100 minutes. 

    Hence, the correct answer is option (a) 100 minutes. 

    Anurag Mishra Professor Answered on 19th February 2016.
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