SOLUTION: Please help me figure out the answer: How much of a 70% alcohol solution and how much of a 30% alcohol solution should be mixed to make 5 liters of a 50% alcohol solution?

Question 545910: Please help me figure out the answer: How much of a 70% alcohol solution and how much of a 30% alcohol solution should be mixed to make 5 liters of a 50% alcohol solution?
Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
Let = liters of 70% solution needed
Let = liters of 30% solution needed
= liters of alcohol in 70% solution
= liters of alcohol in 30% solution
---------------------------------
In words:
( liters of alcohol ) / ( total liters of solution ) = 50%
--------------
given:
(1)
(2)
-----------------------
(2)
(2)
Multiply both sides of 1) by
(1)

and, since
(1)
(1)
(1)
2.5 liters of 70% solution are needed
2.5 liters of 30% solution are needed
check answer:
(2)
(2)
(2)
(2)
OK
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