document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1083425>Question 1083425</A>: <I><SPAN STYLE=\"word-break: break-all;\"> I am not sure if I am posting this in the right place \r<BR>\n" );
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document.write( "A contractor mixes concrete from bags of&#8203; pre-mix. How many bags with 10 % cement should he mix with 4 bags of 12.5% cement to produce a mix containing 11% &#8203;cement?<BR>\n" );
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document.write( "A. 10 Bags<BR>\n" );
document.write( "B. 8 Bags<BR>\n" );
document.write( "C. 6 Bags<BR>\n" );
document.write( "D. 15 bg<BR>\n" );
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document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #697414 by </B><A HREF=/tutors/aboutme.mpl?userid=jim_thompson5910><B>jim_thompson5910(35256)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=jim_thompson5910><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=697414\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Let x = number of 10% bags of cement needed<BR>\n" );
document.write( "The goal is to find the number that replaces x\r<BR>\n" );
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document.write( "Let's say that each bag weighs 100 pounds.\r<BR>\n" );
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document.write( "A single 10% cement bag has 10 pounds of pure cement (0.1*100 = 10)<BR>\n" );
document.write( "x of these bags would have 10x pounds of pure cement<BR>\n" );
document.write( "In total, we have 100*x = 100x pounds of material (cement+other stuff)\r<BR>\n" );
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document.write( "A single 12.5% bag has 12.5 pounds of pure cement (0.125*100 = 12.5)<BR>\n" );
document.write( "Four of these bags would have 4*12.5 = 50 pounds of pure cement<BR>\n" );
document.write( "In total, we have 4*100 = 400 pounds of material (cement+other stuff)\r<BR>\n" );
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document.write( "Mixing the x 10% bags and the four 12.5% bags yields <BR>\n" );
document.write( "<font color=blue>10x+50 pounds</font><BR>\n" );
document.write( "of pure cement\r<BR>\n" );
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document.write( "This would be out of <font color=green>100x+400 pounds</font> total (of cement plus other material)\r<BR>\n" );
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document.write( "Divide the two expressions (10x+50 and 100x+400) and set this ratio equal to the desired percentage we want, which is 11% = 0.11, so<BR>\n" );
document.write( "(<font color=blue>amount of pure cement</font>)/(<font color=green>amount total</font>) = percentage desired<BR>\n" );
document.write( "(<font color=blue>10x+50</font>)/(<font color=green>100x+400</font>) = 0.11\r<BR>\n" );
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document.write( "Solve for x<BR>\n" );
document.write( "(10x+50)/(100x+400) = 0.11<BR>\n" );
document.write( "[(10x+50)/(100x+400)]*(100x+400) = 0.11*(100x+400)<BR>\n" );
document.write( "10x+50 = 0.11*(100x)+0.11*(400)<BR>\n" );
document.write( "10x+50 = 11x+44<BR>\n" );
document.write( "10x+50-44 = 11x+44-44<BR>\n" );
document.write( "10x+6 = 11x<BR>\n" );
document.write( "10x+6-10x = 11x-10x<BR>\n" );
document.write( "6 = x<BR>\n" );
document.write( "x = 6\r<BR>\n" );
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document.write( "Answer: \r<BR>\n" );
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document.write( "We need <font color=red>6 bags</font> of the 10% mix. </SPAN>\n" );
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