IBPS Clerk Prelims Model Paper 8

Let the number of emptying pipes be x and y be the number of filling pipes. According to the problem,
x + y = 6 .… (A)
And 18y/18 – 18x/12 = 1 .… (B)
From (B), 12y – 18x = 12
Or 2y – 3x = 2 .… (C)
From (A) and (C), we get
5x = 10
⇒ x = 2
The answer is 2 pipes, i.e. option (C).