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A pharmacist has an 18% alcohol solution. How much of this solution and how much water must be mixed together
to make 10 liters of a 12% alcohol solution?
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Let x be an amount (the volume in liters) of the 18% solution needed.
Then the water volume is 10-x liters.
The "pure alcohol" contents equation is
0.18*x = 0.12*10.
Solve it for x:
0.18x = 1.2 ---> x = = 6.667.
Hence, 6.667 = liters of the original 18% alcohol solution should be used.
Then the volume of water is 10 - = liters.
Answer. liters of the 18% alcohol solution and liters of water.