document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=621572>Question 621572</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Dmitri needs 7 liters of a 24% solution of sulfuric acid for a research project in molecular biology. He has two supplies of sulfuric acid solution: one is an unlimited supply of 28% solution and the other an unlimited supply of the 14% solution. How many liters of each solution should Dmitri use? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #390832 by </B><A HREF=/tutors/aboutme.mpl?userid=dragonwalker><B>dragonwalker(73)</B></A><img src=\"/images/stars/stars-08.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=dragonwalker><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=390832\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> First look at how each solution is different from the required concentration.\r<BR>\n" );
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document.write( "The 28% is +4% from the required 24%<BR>\n" );
document.write( "The 14% id -10% from the required 24%\r<BR>\n" );
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document.write( "So the effect of the 28% is only 4/10 of the effect of the 14% \r<BR>\n" );
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document.write( "so you need 10/4 times more of the 28% than the 14%\r<BR>\n" );
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document.write( "So let us call the volume of the 14% 'x'<BR>\n" );
document.write( "So the volume of the 28% is10x/4\r<BR>\n" );
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document.write( "As the total volume needed is 7 liters this may be written:\r<BR>\n" );
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document.write( "x + 10x/4 = 7\r<BR>\n" );
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document.write( "solve for x:<BR>\n" );
document.write( "(multiply all by 4 to remove denominator of 10x/4)\r<BR>\n" );
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document.write( "4x + 10x = 28<BR>\n" );
document.write( "14x = 28<BR>\n" );
document.write( "x = 28/14<BR>\n" );
document.write( "x = 2\r<BR>\n" );
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document.write( "So the volume of the 14% is 2 litres and therefore the amount of 28% is 10/4 x 2<BR>\n" );
document.write( "=5\r<BR>\n" );
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document.write( "Check:<BR>\n" );
document.write( "Multiply the effect of each concentration (i.e. the difference between the concentration and desired by the calculated volume needed and add together. If the desired concentration of 24% was reached the answer should be zero.\r<BR>\n" );
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document.write( "2 times -10 + 5 times +4 = 0 </SPAN>\n" );
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