A tank is attached with 30 pipes, some of these are filling pipes and the rest are emptying pipes. Each filling pipe can fill the tank completely in 24 hours and each emptying pipe can empty the tank completely in 18 hours. When all the pipes are opened together, it takes \(1\frac{1}{2}\) hours to fill the tank completely. How many of the given pipes are emptying pipes ?

Question

Question

This question was previously asked in

RRB Group D 28 Sept 2022 Shift 3 Official Paper

Answer 1

Given:

total pipes = 30

filling pipes = 24 hours each

emptying pipes = 18 hours each

Solution:

Let, the filling pipes = 30 - n

emptying pipes = n

(30 - n)/24 - n/18 = 1/1.5

⇒ 90 - 3n - 4n = 72/1.5

⇒ - 7n = 48 - 90

n = 42/7

n = 6 pipes

Hence, the correct option is 4.

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