SOLUTION: How many liters of a 70% alcohol solution must be added to 50 liters of a 40% alcohol solution to produce a 50% alcohol solution?

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Question 1156014: How many liters of a 70% alcohol solution must be added to 50 liters of a 40% alcohol solution to produce a 50% alcohol solution?
Found 2 solutions by josgarithmetic, MathTherapy:
Answer by josgarithmetic(39617) (Show Source):
You can put this solution on YOUR website!
v liters of 70% alcohol
50 liters of 40% alcohol
Want 50% alcohol
v+50 liters, resulting solution volume

.
.

Answer by MathTherapy(10552) (Show Source):
You can put this solution on YOUR website!

How many liters of a 70% alcohol solution must be added to 50 liters of a 40% alcohol solution to produce a 50% alcohol solution?

Let amount of 70% solution be S
Then we get: .7S + .4(50) = .5(S + 50)
.7S + 20 = .5S + 25
.7S - .5S = 25 - 20
.2S = 5
S, or amount of 70% solution to mix, =