Question

Two pipes A and B can separately fill a cistern in 10 and 15 minutes respectively. A person opens both the pipes together when the cistern should have been was full he finds the waste pipe open. He then closes the waste pipe and in another 3 minutes the cistern was full. In what time can the waste pipe empty the cistern when fill ?
A) 8.21 min
B) 8 min
C) 8.57 min
D) 8.49 min

Answer 1

Answer:

(C)

Step-by-step explanation:

1/10 + 1/15 = 1/6 x 3 = 1/2

1 - 1/2 = 1/2

1/10 + 1/15 - 1/x = 1/2

x = 8.57 min

Answer 2

$\underline{\underline{\Huge\mathfrak{Answer ;}}}$

=> (1/10 + 1/15) - 1/18

=> 10/90 = 1/9 ( Approx )

So , Option (C) 8.57 min is the right answer.

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@dmohit432