Rational Functions - Word Problem

Question

You have 0.8 liters of an acid solution whose acid concentration is 95%. How many liters of pure water should be added to lower the concentration to 25%?

Answer 1

Hi Isabella, set up a table of the information known and needed. Let x represent the amount of water needed.

Solution Percent as a decimal Amount Total

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95% .95 .8 .95 * .8

Water 0 x 0

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25% .25 (.8 + x) .25 * (.8 + x)

The totals above the line must equal the totals below the line or:

.95 * .8 = .25 * (.8 + x)

.76 = .20 + .25x

Subtract .20 from both sides:

.56 = .25x

Divide both sides by .25

x = 2.24

2.24 liters of pure water must be added to the amount of acid concentration 95% to make a acid concentration of 25%.

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