Question 535257
I will pretend that I am not a chemist, because from the point of view of a chemist, this problem is so wrong on multiple levels that it makes me want to cry.
Let the volume of water that must be added be {{{x}}}.
The amount of alcohol in the solution is 40% of 12L, or
{{{0.40*12L=4.8L}}}
If that amount is to be 30% of the expected volume (in liters) of {{{12+x}}},
then {{{0.30*(12+x)=4.8}}}
{{{3.6+0.30x=4.8}}} --> {{{0.30x=1.2}}} -->{{{x=1.2/0.30}}} --> {{{x=4.0}}}
You need to add 4.0L water.