SOLUTION: A pharmacist wishes to mix a solution that is 8% minoxidil. She has 70 ml of 5% solution and wishes to add some 10% solution to obtain the desired 8% solution. How much 10% shoul

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Question 862691: A pharmacist wishes to mix a solution that is 8% minoxidil. She has 70 ml of 5% solution and wishes to add some 10% solution to obtain the desired 8% solution. How much 10% should she add?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +x+ = ml of 10% solution to be added
+.1x+ = ml of minoxidil in 10% solution
+.05%2A70+=+3.5+ ml of minoxidil in 5% solution
------------------------
+%28+.1x+%2B+3.5+%29+%2F+%28+x+%2B+70+%29+=+.08+
+.1x+%2B+3.5+=+.08%2A%28+x+%2B+70+%29+
+.1x+%2B+3.5+=+.08x+%2B+5.6+
+.02x+=+2.1+
+x+=+105+
105 ml of 10% solution should be added
check:
+%28+.1x+%2B+3.5+%29+%2F+%28+x+%2B+70+%29+=+.08+
+%28+.1%2A105+%2B+3.5+%29+%2F+%28+105+%2B+70+%29+=+.08+
+%28+10.5+%2B+3.5+%29+%2F+175+=+.08+
+14+=+.08%2A175+
+14+=+14+
OK