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.

If a pipe can fill a tank in x hours, then:

part filled in 1 hour =	1	.
	x

If a pipe can empty a tank in y hours, then:

part emptied in 1 hour =	1	.
	y

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 on opening both the pipes, then

the net part filled in 1 hour =		1	-	1		.
		x		y

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 on opening both the pipes, then

the net part emptied in 1 hour =		1	-	1		.
		y		x