SOLUTION: A pharmacist wishes to mix a solution that is 4% Minoxidil. She has on hand 90 ml of a 2% solution and wishes to add some 6% solution to obtain the desired 4% solution. How much 6

Algebra ->  Customizable Word Problem Solvers  -> Mixtures -> SOLUTION: A pharmacist wishes to mix a solution that is 4% Minoxidil. She has on hand 90 ml of a 2% solution and wishes to add some 6% solution to obtain the desired 4% solution. How much 6      Log On

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Question 1163703: A pharmacist wishes to mix a solution that is 4% Minoxidil. She has on hand 90 ml of a 2% solution and wishes to add some 6% solution to obtain the desired 4% solution. How much 6% solution should she add?
Found 2 solutions by josgarithmetic, MathTherapy:
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
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mix a solution that is 4% Minoxidil. She has on hand 90 ml of a 2% solution and wishes to add some 6% solution to obtain the desired 4% solution. How much 6% solution should she add?
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90%2A0.02%2Bv%2A%280.06%29=%2890%2Bv%29%2A%280.04%29
highlight_green%280.06v%2B0.02%2A90=0.04%28v%2B90%29%29
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0.06v%2B0.02%2A90=0.04v%2B0.04%2A90
%280.06-0.04%29v=0.04%2A90-0.02%2A90
%280.06-0.04%29v=90%280.04-0.02%29
highlight%28v=90%28%280.04-0.02%29%2F%280.06-0.04%29%29%29-------compute this.

Answer by MathTherapy(10552) About Me  (Show Source):
You can put this solution on YOUR website!
A pharmacist wishes to mix a solution that is 4% Minoxidil. She has on hand 90 ml of a 2% solution and wishes to add some 6% solution to obtain the desired 4% solution. How much 6% solution should she add?
Let amount of 6% to mix, be S

We then get: .06S  + .02(90) = .04(S + 90)

.06S + 1.8 = .04S + 3.6

.06S - .04S = 3.6 - 1.8

.02S = 1.8

Amount of 6% to mix, or highlight_green%28matrix%281%2C6%2C+S%2C+%22=%22%2C+1.8%2F.02%2C+%22=%22%2C+90%2C+mL%29%29

OR

As they always say on here, 2% and 6% are being used to get 4%, and since 4% is the half-way point between 2% and 6%, it goes without saying that each amount will be the same, or 90 mL.