SOLUTION: 48. MIXTURE PROBLEM. A pot contains 6L of brine at a concentration of 120g/L. How much of the water should be boiled off to increase the concentration to 200g/L?

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Question 634039: 48. MIXTURE PROBLEM. A pot contains 6L of brine at a concentration of 120g/L. How much of the water should be boiled off to increase the concentration to 200g/L?
Answer by Edwin McCravy(20055) About Me  (Show Source):
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MIXTURE PROBLEM. A pot contains 6L of brine at a concentration of 120g/L. How much of the water should be boiled off to increase the concentration to 200g/L?
Brine is water with salt dissolved in it.

Since there are 6L of the 120g/L brine, there are 6L×130g/L = 780 grams
of salt in those 6 liters of brine.  

Let x = the number of liters of water needed so that those 780 grams of salt
would give it a concentration of 200g/L

780 grams of salt is to x liters of water as 200 grams is to 1 liter of water:

        780%2Fx = 200%2F1

            200x = 780
               x = 780%2F200
               x = 3.9 liters of solution.

Therefore we must reduce the 6L down to 3.9L.

Therefore 6L - 3.9L = 2.1 liters of water must be boiled off.

Answer: 2.1L

Edwin