SOLUTION: Antifreeze 1 is 18% alcohol and Antifreeze 2 is 10% alcohol. How many liters of 1 should be mixed with 7.5L of Antifreeze 2to get a mix that's 15% alcohol?

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Question 1142753: Antifreeze 1 is 18% alcohol and Antifreeze 2 is 10% alcohol. How many liters of 1 should be mixed with 7.5L of Antifreeze 2to get a mix that's 15% alcohol?
Found 2 solutions by josgarithmetic, greenestamps:
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
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How many liters of 1 should be mixed with 7.5L of Antifreeze 2to get a mix that's 15%,....?
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x, volume of the 18% alcohol antifreeze

0.18x%2B0.1%2A7.5=0.15%28x%2B7.5%29
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Answer by greenestamps(13200) About Me  (Show Source):
You can put this solution on YOUR website!


15% is 5/8 of the way from 10% to 18%.

That means 5/8 of the total should be the 18% antifreeze.

Given that the 7.5L of the 18% antifreeze is 5/8 of the total, use any of a number of methods to determine that we need 4.5L of the 10% antifreeze.

ANSWER: 4.5L of the 10% antifreeze should be mixed with the 7.5L of 18% antifreeze.