Example #2:

We have 1 liter of a stock solution (5 moles/liter) of glucose.
We want to make precisely 200 ml of a new solution (1 mole/liter) of glucose.

What volume of stock solution and what volume of water do we have to mix to do so?

Vol new x conc new = vol st x conc st
200 x 1 = vol st x 5

The volume of stock solution needed is:

vol st= (200x1)/5 = 40 ml of stock solution

The volume of water needed is:

200 ml - 40 ml = 160 ml of water.

Again this is a (40ml:160ml) 1:4 dilution .