Question 126

Pipes A and B together can fill a tank in 16 hours, where as pipe C alone can empty the full tank in 24 hours. A and B were opened together for 10 hours and then closed. Pipe C was then opened. The tank will now be emptied by C in:

Solution

let pipe A = a , pipe B=b and pipe C= c

According to question $$\dfrac{1}{a} + \dfrac{1}{b} = \dfrac {1}{16} $$

and $$\dfrac{1}{c} = - \dfrac{1}{24}$$

pipe a and pipe b both opend 10 hour together and t time taken empty by pipe c

so $$(\dfrac{1}{a} + \dfrac{1}{b}) - t\dfrac{1}{c} = 0 $$

$$\Rightarrow \dfrac{10}{16} = \dfrac{t}{24} $$

$$\Rightarrow t = 15 hours Ans $$

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