SOLUTION: A pharmacist wishes to mix a solution that is 7% Minoxidil. She has on hand 90 ml of a 5% solution and wishes to add some 9% solution to obtain the desired 7% solution. How much 9%

Algebra ->  Customizable Word Problem Solvers  -> Mixtures -> SOLUTION: A pharmacist wishes to mix a solution that is 7% Minoxidil. She has on hand 90 ml of a 5% solution and wishes to add some 9% solution to obtain the desired 7% solution. How much 9%      Log On

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Question 648125: A pharmacist wishes to mix a solution that is 7% Minoxidil. She has on hand 90 ml of a 5% solution and wishes to add some 9% solution to obtain the desired 7% solution. How much 9% solution should she add?
Thanks!

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
+x+ = ml of 9% solution needed
+.09x+ = ml of Minoxidil in 9% solution
+.05%2A90+=+4.5+ ml of Minoxidil in 5% solution
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+%28+4.5+%2B+.09x+%29+%2F+%28+x+%2B+90+%29+=+.07+
+4.5+%2B+.09x+=+.07%2A%28+x+%2B+90+%29+
+4.5+%2B+.09x+=+.07x+%2B+6.3+
+.02x+=+6.3+-+4.5
+.02x+=+1.8+
+x+=+90+
90 ml of 9% solution are needed
check:
+%28+4.5+%2B+.09x+%29+%2F+%28+x+%2B+90+%29+=+.07+
+%28+4.5+%2B+.09%2A90+%29+%2F+%28+90+%2B+90+%29+=+.07+
+%28+4.5+%2B+8.1+%29+%2F+180+=+.07+
+12.6++=+.07%2A180+
+12.6+=+12.6+
OK