SOLUTION: You need a 80% alcohol solution. On hand, you have a 260 mL of a 45% alcohol mixture. How much pure alcohol will you need to add to obtain the desired solution?

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Question 1036670: You need a 80% alcohol solution. On hand, you have a 260 mL of a 45% alcohol mixture. How much pure alcohol will you need to add to obtain the desired solution?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +x+ = ml of pure alcohol needed
+.45%2A260+=+117+ ml of pure alcohol in 45% solution
---------------------
+%28+x+%2B+117+%29+%2F+%28+x+%2B+260+%29+=+.8+
+x+%2B+117+=+.8%2A%28+x+%2B+260+%29+
+x+%2B+117+=+.8x+%2B+208+
+.2x+=+91+
+x+=+455+
455 ml of pure alcohol should be added
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check:
+%28+x+%2B+117+%29+%2F+%28+x+%2B+260+%29+=+.8+
+%28+455+%2B+117+%29+%2F+%28+455+%2B+260+%29+=+.8+
+572+%2F+715+=+.8+
+.8+=+.8+
OK