Question 1175706
.


            Both the solution and the answer by @josgarithmetic are  INCORRECT.


            I came to bring a correct solution.



<pre>
You mix x liters of the 40% alcohol solution and (12-x) liters of the 60% alcohol solution.


Under this approach, the total volume of 12 liters of the resulting mixture is just provided,

and all you need to care about is to provide the requested concentration of 45% for the mixture.


So, you write this equation for the concentration

    {{{(0.4x + 0.6*(12-x))/12}}} = 0.45,    (1)


or, which is the same

    0.4x + 0.6*(12-x) = 0.45*12       (2)


From this equation


    x = {{{(0.45*12 - 0.6*12)/(0.4-0.6)}}} = 9 liters.


<U>ANSWER</U>.  9 liters of the 40% solution  and  the rest, (12-9) = 3 liters of the 60% solution.


<U>CHECK</U>.   {{{(0.4*9 + 0.6*3)/12}}} = 0.45 = 45%  final concentration   ! Correct !
</pre>

Solved.


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It is a standard and typical mixture problem.


For introductory lessons covering various types of mixture word problems see

&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/Typical-word-problems-on-mixtures-from-the-archive.lesson>Typical word problems on mixtures from the archive</A>

in this site.


You will find there ALL TYPICAL mixture problems with different methods of solutions,
explained at different levels of detalization, &nbsp;from very detailed to very short.


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


Also, &nbsp;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.