**Home » Aptitude Formulas » Pipes and Cisterns Important formulas**

**Pipes and Cisterns Important formulas:**

**1. 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.

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

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

**4**.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

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