SOLUTION: three liters of alcohol water mixture contains 40% alcohol. how much alcohol must be evaporated and replaced by water in order to produce 30% alcohol mixture?

Question 1008876: three liters of alcohol water mixture contains 40% alcohol. how much alcohol must be evaporated and replaced by water in order to produce 30% alcohol mixture?
Answer by josgarithmetic(39617) (Show Source): You can put this solution on YOUR website!
v, the amount of alcohol to be removed and replaced with v volume of water. Note, the water
does not contribute any quantity of alcohol, being 0% alcohol. The volume of the solution
after evaporation and addition will still be the same 3 liters.

Using fractions instead of percents,

and understand the starting amount of alcohol was 0.4*3 LITERS, and v liters of alcohol
to remove is as 100% alcohol; the starting solution is 40% alcohol.

Now, just solve for v.

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