SOLUTION: How many liters of pure alcohol need to be added to seven liters of 21% alcohol solution to produce a mixture which is 44.7% alcohol?

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Question 159493: How many liters of pure alcohol need to be added to seven liters of 21% alcohol solution to produce a mixture which is 44.7% alcohol?
Answer by KnightOwlTutor(293) About Me  (Show Source):
You can put this solution on YOUR website!
X= number of Liters of pure alcohol needed
Convert the % to decimal format ie 21%=.21
Pure alcohol is 100% decimal format is 1
The algebraic equation for this is:
X+7(.21)=.447(7+X)
The total volume on both sides of the equation must be the same.
Use the distributive property to get
X+1.47=3.129+.447X
Subtract .447 from both sides
Subtract 1.47 from both sides
0.553X=1.654
X=3 Liters of pure alcohol
To confirm plug in 3 for the variable X in the algebraic equation.