Word Problems

How many liters of pure water must be mixed with a 4 liter mixture of 25% antifreeze to produce a 23% mixture?
First you must understand the meanings of the words in the problem.
So what is the definition of mixture and antifreeze?   answer

w = the # of liters of pure water we will mix with the antifreeze
In the equation we will identify the amount of antifreeze in each fluid.

0%w + 25%(4 liters) = 23% (4 liters + w liters )
.25(4) = .23(4) + .23 w
1 = .92 + .23w
1 - .92 = .23w
.08 = .23w
.08 ÷ .23 = w
.348 = w
Therefore approximately .348 liters of pure water must be mixed with the antifreeze too make the 23% mixture.

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How many liters of a 67% sulfuric acid solution must be added to 3 liters of a 27% solution of sulfuric acid to obtain a 42% solution of sulfuric acid?
answer
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