Question 1100474
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<pre>
Let V be the volume of water to add, in milliliters.

Then in the new mixture you have 0.25*48 mL of the pure acid, same amount of the pure acid as in the original 25% solution.


You add the volume V of water, and then your new mixture has the volume (48+V).


The concentration of acid in  the new solution is the ratio {{{(0.25*48)/(48+V)}}} of the pure acid in the new solution to its volume.


This ratio must be 15%, as the condition requires.


It gives you the "concentration equation"

{{{(0.25*48)/(48+V)}}} = 0.15.         <<<---=== It is your basic equation, and it expresses the fact that the concentration of the new solution is 15%.


It is your basic equation, and as soon you got it, the setup step is completed.


To solve the equation, multiply its both sides by (48+V). You will get

0.25*48 = 0.15*(48+V).


Simplify it further and solve for V:

12 = 7.2 + 0.15V  ====>  0.15V = 12-7.2 = 4.8  ====>  V = {{{4.8/0.15}}} = 32.


<U>Answer</U>.  32 mL of water must be added.


<U>Check</U>.   {{{(0.25*48)/(48+32)}}} = 0.15.  ! Correct: the concentration condition is SATISFIED !
</pre>

Solved.


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There is entire bunch of introductory lessons covering various types of mixture problems

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=http://www.algebra.com/algebra/homework/word/mixtures/Mixture-problems.lesson>Mixture problems</A>

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=http://www.algebra.com/algebra/homework/word/mixtures/More-Mixture-problems.lesson>More Mixture problems</A>

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=http://www.algebra.com/algebra/homework/word/mixtures/Solving-typical-mixture-problems.lesson>Solving typical word problems on mixtures for solutions</A> 

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/word/mixtures/Word-problems-on-mixtures-for-antifreeze-solutions.lesson>Word problems on mixtures for antifreeze solutions</A> 

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/word/mixtures/Word-problems-on-mixtures-for-alloys.lesson>Word problems on mixtures for alloys</A> 

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/word/mixtures/Typical-word-problems-on-mixtures-from-the-archive.lesson>Typical word problems on mixtures from the archive</A>

in this site.


Read them and become an expert in solution mixture word problems.


Also, you have this free of charge online textbook in ALGEBRA-I in this site

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/quadratic/lessons/ALGEBRA-I-YOUR-ONLINE-TEXTBOOK.lesson>ALGEBRA-I - YOUR ONLINE TEXTBOOK</A>.


The referred lessons are the part of this textbook in the section "<U>Word problems</U>" under the topic "<U>Mixture problems</U>".



Save the link to this online textbook together with its description


Free of charge online textbook in ALGEBRA-I
https://www.algebra.com/algebra/homework/quadratic/lessons/ALGEBRA-I-YOUR-ONLINE-TEXTBOOK.lesson


to your archive and use it when it is needed.