Question 85501
A pharmacist has 1 liter of a solution that is 22% alcohol.  How much pure alcohol must be added to bring the solution up to 27% alcohol
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Rule: Follow the active ingredient.
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22% solution DATA:
Amount = 1 liter ; Amt of active ingredient = 0.22*1=0.22 liters
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Pure Alcohol DATA:
Amount = x liters ; Amt of active ingredient = 100%*x = x liters
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27% Mixture DATA:
Amount = 1+x liters ; Amt of active ingredient = 0.27(1+x)=0.27+0.27x liters
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EQUATION:
active + active = active
0.22 + x = 0.27+0.27x
0.05 = 0.73x
x= 0.0685 liters (Amount of 100% alcohol that must be added)
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Cheers,
Stan H.