Question 1152168: How much water must be evaporated from 17qt of a 65% antifreeze solution to produce an 85% solution? Found 2 solutions by ikleyn, greenestamps:Answer by ikleyn(52788) (Show Source):
Let W be the volume of water to be evaporated.
The amount of the pure antifreeze in the original mixture is 0.65*17 qt.
The volume of the mixture after evaporating water is (17 - W) qt.
The new concentration equation is
= 0.85. (1)
To solve it, multiply both sides by (17-W). You will get
0.65*17 = 0.85*(17-W).
From the equation,
W = = 4.
ANSWER. 4 qt of water must be evaporated.
To check the answer, substitute the found value W= 4 into the basic equation (1).
Use the percentages to determine how many quarts are in the solution after the water has been evaporated; then use that to determine how much water needs to be evaporated.
There need to be 13 quarts in the final mixture for it to be 85% antifreeze; since there were 17 quarts at the start, 4 quarts were evaporated.
