SOLUTION: 4) John wants to make a 100 ml of 5% alcohol solution mixing a quantity of a 2% alcohol solution with a 7% alcohol solution. What are the quantities of each of the two solutions (2

Question 425465: 4) John wants to make a 100 ml of 5% alcohol solution mixing a quantity of a 2% alcohol solution with a 7% alcohol solution. What are the quantities of each of the two solutions (2% and 7%) he has to use?
Answer by htmentor(1343) (Show Source): You can put this solution on YOUR website!
We need to make 100 ml of 5% acid solution. This means we need to obtain 5 ml of acid and 100 ml of solution.
Let x = the number of ml of 2% solution
Then 100 - x will be the number of ml of 7% solution
We need to find x such that
5 = 0.02x + 0.07(100-x)
5 = -0.05x + 7 -> -0.05x = -2 -> x = 40 ml
So the quantities are: 40 ml 2% solution and 60 ml 7 % solution
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