The approach to solve time and work questions is the same as the questions on time and work.

In this case, the filling rate or capacity of the pipes and given and then question asks about the time it will take to fill a tank or about the capacity of the tank. 

A pipe is connected to a tank or cistern. It is used to fill or empty the tank; accordingly, it is called an inlet or an outlet.

Inlet: A pipe which is connected to fill a tank is known as an inlet.

Outlet: A pipe which is connected to empty a tank is known as an outlet

Two pipes A and B can fill the tank in 24 hours and 36 hours respectively. If both pipes are opened simultaneously, how much time will it take to fill the tank?

a) 14 hrs 24 mins          b) 12 hrs 48 mins          c) 12 hrs 24 mins          d) 14 hrs 48 mins

Solution:

Pipe A 1 hr’s work = 1 / 24, Pipe B 1 hr’s work = 1 / 36

(A + B)’s 1 hr’s work = (1 / 24) + (1 / 36) = 5 / 72

⸫ Tank is filled in (72 / 5) hours = 14 hrs 24 mins.

Answer: a

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