Question

a bath is supplied with water from two pipes one of which can fill it in 25/2 min , other in 15 min, there is also a discharging pipe which could empty it, when filled, in 10 min . the first pipe is open alone for 4 min . , and then the first and second open together for 1 min , if now the third pipe is opened as well , how long will it take to fill the bath ?

Answer 1

Solution is here Let the capacity of cistern be 'x' ltrs Let's Talk about filling pipes Each filling pipe can fill the cistern in 6 min = x ltrs It's 1 min work = x/6 ltrs So 10 filling pipes 1min work = 10x/6 ltrs Now talk about emptying pipes Each emptying pipe can empty the cistern in 8 min = x ltrs Each emptying pipe 1min work = -x/8 ltrs 6 emptying pipes 1 min work = -6x/8 ltrs All pipes are open so 10x/6 - 6x/8 = 22 ltrs From solving above equation we will get the value of x = 24 ltrs which is the capacity of the tank. Hope you guys understand well 
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