Need an opinion on if this is a good are bad idea.

Dominion 2L has the following

Active ingredient Imidaloprid 21.4%
Other ingredients 79.6%
Container size is 27.5 oz

79.6% of 27.5 oz = 21.89 oz. If I add 21.89 oz to the bottle this should give me a active ingredient of Imidaloprid of 10.7% and the container size is now 49.39 oz. Am I doing it correct? If this is correct I should be able to apply this to any size container Correct? This would allow me to use 4ml which is what advatage calls for a 55lb and up dog.

Advantage has 9.1% this would give me 10.7%. Add a little more water you can get it down to 9% if needed..

Thanks

klsparrow