Aptitude - Pipes and Cistern

Inlet

A pipe connected with a tank or a cistern or a reservoir, that fills it, is known as an inlet.

Outlet

A pipe connected with a tank or cistern or reservoir, emptying it, is known as an outlet.

Formulas / Concept

If a pipe can fill a tank in x hours, then part filled in 1 hour = 1x

If a pipe can empty a tank in y hours, then part emptied in 1 hour = 1y

If a pipe can fill a tank in x hours and another pipe can empty the full tank in y hours
(where y > x), then net part filled in 1 hour = 1x − 1y

If a pipe can fill a tank in x hours and another pipe can empty the full tank in y hours
(where x > y), then net part filled in 1 hour = 1y − 1x