Question 853381
A chemist has 5% and 40% solutions of acid available. How many liters of each solution should by mixed to obtain 5 liters of a 20% acid solution? 
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Quantity: x + y = 5 liters
Acid:::: 0.05x + 0.40y = 0.20*5
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Multiply thru by 100 and substitute for "y" to get:
5x + 40(5-x) = 20*5
5x + 40*5 - 40x = 20*5
-35x = -20*5
x = (1/7)20
x = 2.86 liters of 5% solution
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y = 5-y = 5-2.86 = 2.14 liters of 40% solution
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Cheers,
Stan H.
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