SOLUTION: How much pure water must be mixed with 2 pints of 50% developer to produce a mixture that is 31% developer

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Question 744895: How much pure water must be mixed with 2 pints of 50% developer to produce a mixture that is
31% developer
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +w+ = pints of water needed
+.5%2A2+=+1+ pint of developer in 50% solution
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+1+%2F+%28+2+%2B+w+%29+=+.31+
+.31%2A%28+2+%2B+w+%29+=+1+
+2+%2B+w+=+1%2F.31+
+w+=+3.2258+-+2+
+w+=+1.2258+ pints
--------------------
check:
+1+%2F+%28+2+%2B+w+%29+=+.31+
+1+%2F+%28+2+%2B+1.2258+%29+=+.31+
+1+%2F+3.2258+=+.31+
+.31+=+.31+
OK