Exercise :: Pipes and Cistern  Important Formulas
 Pipes and Cistern  Important Formulas
 Pipes and Cistern  General Questions
 Pipes and Cistern  Data Sufficiency 1
 Pipes and Cistern  Data Sufficiency 2

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 x > y), then on opening both the pipes, then
the net part emptied in 1 hour = 1  1 . y x