document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=443683>Question 443683</A>: <I><SPAN STYLE=\"word-break: break-all;\"> a mixture of 8% disenfectants solution is to be made from 10 % and 7% diseenfectant solution. How much of ech solution should be used if 30 galllons of 8% solution are needed? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #305971 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=305971\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> What are we told the goal is produce 30 gallons of an 8% disinfectant.<BR>\n" );
document.write( "We have unlimited supplies of 10% and 7% solutions to mix together.<BR>\n" );
document.write( "With most mixture problems it helps to figure out how much \"pure\" stuff you will have.<BR>\n" );
document.write( ".08*30 = 2.4 gallons of pure stuff in the 30 gallons.<BR>\n" );
document.write( "Setting up the specific equation to solve uses this information.<BR>\n" );
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document.write( "First, <BR>\n" );
document.write( "x = amount of 10% solution we will use,<BR>\n" );
document.write( "so<BR>\n" );
document.write( "30-x = amount of 7% solution we will use.<BR>\n" );
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document.write( "Second,<BR>\n" );
document.write( "x*.10 + (30-x)*.07 = 30*.08<BR>\n" );
document.write( ".10x + 2.1 - .07x = 2.4<BR>\n" );
document.write( "Multiply by 100 to eliminate the decimals<BR>\n" );
document.write( "10x + 210 - 7x = 240<BR>\n" );
document.write( "3x + 210 = 240<BR>\n" );
document.write( "3x = 30<BR>\n" );
document.write( "x = 10 gallons of 10% solution<BR>\n" );
document.write( "30-x = 20 gallons of 7% solution<BR>\n" );
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document.write( "Always check your work!<BR>\n" );
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document.write( "In this case, we know we have 30 gallons (10+20), so we need to check how much pure stuff we have contained in the 30 gallons.<BR>\n" );
document.write( "10*.10 = 1 gallon of pure stuff coming from the 10% component.<BR>\n" );
document.write( "20*.07 = 1.4 gallons of pure stuff coming from the 7% component.<BR>\n" );
document.write( "1 + 1.4 = 2.4 gallons of pure stuff contained in the 30 gallons, which is what we needed.<BR>\n" );
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document.write( "Answer:  Use 10 gallons of 10% solution and 20 gallons to 7% solution to produce 30 gallons of 8% solution.<BR>\n" );
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document.write( "Done. </SPAN>\n" );
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