SOLUTION: How many ounces of a 13% alcohol solution must be mixed with 3 ounces of a 20% alcohol solution to make a 16% alcohol solution?

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Question 1147440: How many ounces of a 13% alcohol solution must be mixed with 3 ounces of a 20% alcohol solution to make a 16% alcohol solution?
Found 2 solutions by josgarithmetic, greenestamps:
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
x, amount of the 13% alcohol

13x%2B20%2A3=16%28x%2B3%29

13x%2B3%2A20=16x%2B16%2A3
20%2A3-16%2A3=16x-13x
4%2A3=3x
highlight%28x=4%29

Answer by greenestamps(13200) About Me  (Show Source):
You can put this solution on YOUR website!


A quick non-algebraic method for solving mixture problems like this....

(1) The target of 16% is 3/7 of the way from 13% to 20%. (Picture the three percentages on a number line: 13 to 16 is 3; 13 to 20 is 7; 16 is 3/7 of the way from 13 to 20.)

(2) That means 3/7 of the mixture is the higher percentage ingredient.

That 3/7 of the mixture is 3 ounces, so the other 4/7 of the mixture is 4 ounces.

ANSWER: 4 ounces of the 13% solution