document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=519758>Question 519758</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A hospital staff mixed a 75% disinfectant solution with a 25% disinfectant solution. How many liters of each were used to make 10 L of a 40% disinfectant solution?<BR>\n" );
document.write( "75% solution  ?     L  <BR>\n" );
document.write( "25% solution    ?   </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #345770 by </B><A HREF=/tutors/aboutme.mpl?userid=oberobic><B>oberobic(2304)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=oberobic><IMG SRC=http://www.algebra.com/images/aboutme-small.gif BORDER=0 alt=\"About Me\" VALIGN=MIDDLE></A>&nbsp;<IMG SRC=http://www.algebra.com/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=345770\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> When doing mixture or solution problems, focus on how much 'pure' stuff you need.<BR>\n" );
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document.write( "10 liters of 40% disinfectant will have 10*.4 = 4.0 liters of pure disinfectant and 6.0 liters of water (or some other solvent).<BR>\n" );
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document.write( "x = liters of 75% solution to use<BR>\n" );
document.write( "y = liters of 25% solution to use<BR>\n" );
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document.write( "however, we know<BR>\n" );
document.write( "x + y = 10<BR>\n" );
document.write( "so<BR>\n" );
document.write( "y = 10-x<BR>\n" );
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document.write( "That approach means we have only one unknown and, therefore, only need one equation to solve it.<BR>\n" );
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document.write( ".75*x + .25(10-x) = .40(10)<BR>\n" );
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document.write( "multiply through by 100 to eliminate the decimals<BR>\n" );
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document.write( "75x + 25(10-x) = 40(10)<BR>\n" );
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document.write( "75x + 250 - 25x = 400<BR>\n" );
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document.write( "50x = 150<BR>\n" );
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document.write( "x = 3<BR>\n" );
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document.write( "y = 10-3<BR>\n" );
document.write( "y = 7<BR>\n" );
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document.write( "Answer: Mix 3 liters of 75% disinfectant with 7 liters of 25% disinfectant to produce 10 liters of 40% solution.<BR>\n" );
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document.write( "Check the answer by checking how much pure stuff you have.<BR>\n" );
document.write( ".75*3 = 2.25<BR>\n" );
document.write( ".25*7 = 1.75<BR>\n" );
document.write( "2.25 + 1.75 = 4.00 liters of pure disinfectant in the 10 liters, which is a 40% solution.<BR>\n" );
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document.write( "Done. </SPAN>\n" );
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