SOLUTION: How many liters of water should be added to 3 liters of a 70 percent alcohol solution to obtain a 50 percent solution

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Question 1037557: How many liters of water should be added to 3 liters of a 70 percent alcohol solution to obtain a 50 percent solution
Answer by ikleyn(52782) About Me  (Show Source):
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How many liters of water should be added to 3 liters of a 70 percent alcohol solution to obtain a 50 percent solution
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%283%2A0.7%29%2F%283+%2B+w%29 = 0.5     ("alcohol percentage contents" equation)

3*0.7 = 0.5*(3 + w),

2.1 = 1.5 + 0.5w,

0.5w = 2.1 -1.5,

0.5w = 0.6   --->  w = 0.6%2F0.5 = 1.2.

Answer.  1.2 liters of water.