Question 1203419
12 ml of a 65% alcohol solution was mixed with 8 ml of an 80% alcohol solution.
What is the concentration of the mixture?
<pre>
The concentration is the percentage of alcohol in the final solution; let
that be x:

                ml of solution| % expressed as a decimal| ml of pure alcohol
1st solution          12      |           0.65          |   12(0.65) = 7.8
2nd solution           8      |           0.80          |    8(0.80) = 6.4
final solution        20      |             x           |             14.2

20x = 14.2

  x = 0.71 = 71%   <--answer

Edwin</pre>