document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=206901>Question 206901</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Hello, I need help on one of my questions for summer. I did the rest im just stuck on this one, I really don't know how to do ratios. PLZ HELP!<BR>\n" );
document.write( "okay so the question is:<BR>\n" );
document.write( "According to the U.S Mint, pennies are made of 97.5 percent zinc and 2.5 percent copper by mass. Copper has a density of 8.96 grams of mass per cubic centimeter of volume. Zinc has a density of 7.13 grams of mass per cubic centimeter of volume. <BR>\n" );
document.write( "A. What is the ratio of the mass of zinc to the mass of copper in a penny?<BR>\n" );
document.write( "B. What is the ratio of the volume of zinc to the volume of copper in a penny?<BR>\n" );
document.write( "C. You have measured the mass of some pennies that were minted before 1982, when they had a different composition than they do today. They were still made of zinc and copper, but in a different ratio. You have found that one penny has a mass of 3.1 grams, and has a volume of 0.35 cubic centimeters. Find the mass of the copper in this penny.<BR>\n" );
document.write( "whoa!<BR>\n" );
document.write( "Thank You SOO much!! If you could just help me with A and B i would probably be able to figure out the last one. Thank u thank u! </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #156481 by </B><A HREF=/tutors/aboutme.mpl?userid=scott8148><B>scott8148(6628)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=scott8148><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=scott8148><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=156481\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> A. \"97.5 percent zinc and 2.5 percent copper by mass\"<BR>\n" );
document.write( "___ mass ratio is ... 97.5% : 2.5% ... or ... 39 : 1 ... or ... 39\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "B. density is the ratio of mass to volume ___ so to find volume; divide mass by density<BR>\n" );
document.write( "___ using the result from A ___ volume ratio is ... (39 / 7.13) : (1 / 8.96) ... or ... 49.01 (approx)\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "C. (mass of copper) / (density of copper) = volume of copper<BR>\n" );
document.write( "___ (mass of zinc) / (density of zinc) = volume of zinc<BR>\n" );
document.write( "___ (volume of copper) + (volume of zinc) = .35\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "let x = \"mass of copper\" ___ (x / 8.96) + ((3.1 - x) / 7.13) = .35\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "multiplying by (8.96)(7.13) ___ 7.13x + 27.78 - 8.96x = 22.36 (approx)\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "-1.83x = -5.42 ___ x = 2.96 g (approx) </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );