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:
part filled
in 1 hour = 1/x.

3. If a pipe
can empty a tank in

*y hours*, then:
part emptied
in 1 hour = 1/y.

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
the net part
filled in 1 hour = ((1/x) – (1/ y)).

5. 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/y) – (1/ x)).