Question 1203419
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Here is an informal method for solving this kind of 2-part mixture problem that is completely different from the standard formal algebraic methods shown by the other tutors....<br>
The fraction of the mixture that is 80% alcohol is 8/(12+8) = 8/20 = 2/5.<br>
That means the percentage of the mixture is 2/5 of the way from 65% to 80%.<br>
From 65% to 80% is a difference of 15%; 2/5 of that is 6%.  The percentage of the mixture is 65+6 = 71%.<br>
ANSWER: 71%<br>