SOLUTION: How much pure water must be mixed with 15 ounce of a 30% alcohol solution to obtain a 25% alcohol solution hint pure water is 0% alcohol

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Question 1041329: How much pure water must be mixed with 15 ounce of a 30% alcohol solution to obtain a 25% alcohol solution hint pure water is 0% alcohol
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +w+ = ounces of water needed
+.3%2A15+=+4.5+ ounces of alcohol is 30% solution
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+4.5+%2F+%28+w+%2B+15+%29+=+.25+
+4.5+=+.25%2A%28+w+%2B+15+%29+
+4.5+=+.25w+%2B+3.75+
+.25w+=+.75+
+w+=+3+
3 ounces of water is needed
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check:
+4.5+%2F+%28+w+%2B+15+%29+=+.25+
+4.5+%2F+%28+3+%2B+15+%29+=+.25+
+4.5+=+.25%2A18+
+4.5+=+4.5+
OK