SOLUTION: A 4-liter container contains a mixture with a concentration of 50%. How much of this mixture must be withdrawn and replaced by 100% concentration to bring the mixture up to 75% con

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Question 821424: A 4-liter container contains a mixture with a concentration of 50%. How much of this mixture must be withdrawn and replaced by 100% concentration to bring the mixture up to 75% concentration?
Found 2 solutions by stanbon, richwmiller:
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
A 4-liter container contains a mixture with a concentration of 50%. How much of this mixture must be withdrawn and replaced by 100% concentration to bring the mixture up to 75% concentration?
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Equation:
active - active + active = active
0.50*4 - 0.50x + 1*x = 0.75*4
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50*4 - 50x + 100x = 75*4
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50x = 25*4
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x = 2 liters (amt. of mixture to be removed and replaced.
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Cheers,
Stan H.
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Answer by richwmiller(17219) About Me  (Show Source):
You can put this solution on YOUR website!
.5*a+b=.75*4,
.5*a+b=3,
a+b=4
a=2 b=2
remove 2 liters of 50 % mixture and add 2 liters of 100%