SOLUTION: How many quarts of an 80% alcohol solution must be added to 10 quarts of a 50% alcohol solution to give a 70% solution?

Question 1172280: How many quarts of an 80% alcohol solution must be added to 10 quarts of a 50% alcohol solution to give a 70% solution?
Found 3 solutions by josgarithmetic, MathTherapy, greenestamps:
Answer by josgarithmetic(39617)   (Show Source): You can put this solution on YOUR website!

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Answer by MathTherapy(10552)   (Show Source): You can put this solution on YOUR website!

How many quarts of an 80% alcohol solution must be added to 10 quarts of a 50% alcohol solution to give a 70% solution?

He's WRONG, again.
The amount needed is NOT 2 quarts, and so,
Answer by greenestamps(13200)   (Show Source): You can put this solution on YOUR website!

A solution without formal algebra....

(1) 70% is 2/3 of the way from 50% to 80% (picture the three percentages on a number line....)

(2) That means 2/3 of the mixture is the 80% solution.

So the 10 quarts of the 50% solution is 1/3 of the mixture; and that means the 2/3 of the mixture is 20 quarts.

ANSWER: 20 quarts

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