document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1184175>Question 1184175</A>: <I><SPAN STYLE=\"word-break: break-all;\"> how many quarts of pure antifreeze must be added to 4 quarts of a 50% antifreeze solution to obtain a 60% antifreeze solution? (hint: pure antifreeze is 100% antifreeze) round to nearest tenth as needed.  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #814719 by </B><A HREF=/tutors/aboutme.mpl?userid=greenestamps><B>greenestamps(13200)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=greenestamps><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/cgi-bin/show-face.mpl?user=greenestamps><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=814719\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <br><BR>\n" );
document.write( "The response from the other tutor is not much help to a student who is trying to learn HOW to set up and solve this kind of problem....<br><BR>\n" );
document.write( "Let x be the number of quarts of 100% antifreeze to add.<br><BR>\n" );
document.write( "The antifreeze in the two ingredients is 100% of x quarts, plus 50% of the 4 quarts you started with; and it is 60% of the total (x+4) quarts:<br><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=100%28x%29%2B50%284%29=60%28x%2B4%29 ALIGN=MIDDLE  ALT=\"100%28x%29%2B50%284%29=60%28x%2B4%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><br><BR>\n" );
document.write( "Solve using basic algebra... I leave that to you.<br><BR>\n" );
document.write( "If a formal algebraic solution is not required, here is a quick and easy way to solve any 2-part \"mixture\" problem like this.<br><BR>\n" );
document.write( "Picture the percentages of the two ingredients and the final mixture on a number line -- 50, 60, and 100; observe/calculate that 60% is 1/5 of the way from 50% to 100%. (50 to 100 is a difference of 50; 50 to 60 is a difference of 10; 10/50 = 1/5.)<br><BR>\n" );
document.write( "That means 1/5 of the mixture is the 100% antifreeze that you are adding.<br><BR>\n" );
document.write( "So the 4 quarts you started with is 4/5 of the mixture; that means the 1/5 of the mixture that you added is 1 quart.<br><BR>\n" );
document.write( "ANSWER: add 1 quart of 100% antifreeze<br><BR>\n" );
document.write( "CHECK:<BR>\n" );
document.write( ".50(4)+1.00(1)=2+1=3<BR>\n" );
document.write( ".60(5)=3<br><BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );