SOLUTION: You have 0.35 liters of an acid solution whose acid concentration is 15%. How many liters of pure water should be added to lower the concentration to 7%?

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Question 961974: You have 0.35 liters of an acid solution whose acid concentration is 15%. How many liters of pure water should be added to lower the concentration to 7%?
Found 3 solutions by lwsshak3, ikleyn, josgarithmetic:
Answer by lwsshak3(11628)   (Show Source):
You can put this solution on YOUR website!
You have 0.35 liters of an acid solution whose acid concentration is 15%. How many liters of pure water should be added to lower the concentration to 7%?
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let x=amt of pure water should be added
15%*35=7%(35+x)
5.25=2.45+.07x
.07x=2.80
x=40
How many liters of pure water should be added to lower the concentration to 7%? 40

Answer by ikleyn(53906)   (Show Source):
You can put this solution on YOUR website!
.
You have 0.35 liters of an acid solution whose acid concentration is 15%.
How many liters of pure water should be added to lower the concentration to 7%?
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        @lwsshar3 in his post gives an answer 40.
        40 of what ? Liters ?
        But this is an absurd.

        There is a rude error in calculations by @lwsshar3.
        I came to bring a correct solution.

let x=amt of pure water should be added (in liters).
0.15*0.35 = 0.07*(0.35+x)
0.0525 = 0.0245 + 0.07x
0.07x = 0.0525 - 0.0245
0.07x = 0.028
x = 0.028/0.07 = 0.4.
How many liters of pure water should be added to lower the concentration to 7%?     0.4 of a liter.

CHECK.     The final concentration is    = 0.07,   or   7%.     ! precisely correct !

Solved correctly.

The lesson to learn: when you make calculations, keep the dimensions consistent and be accurate.

Answer by josgarithmetic(39832)   (Show Source):
You can put this solution on YOUR website!
w, amount of water to add, assuming as volume (liters)

Solve!