document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=377680>Question 377680</A>: <I><SPAN STYLE=\"word-break: break-all;\"> i need help with this problem: This is the model showing the percentage of Americans with heart disease who are \"x\" years old:\r<BR>\n" );
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document.write( "                           90/1+271e^-0.122x<BR>\n" );
document.write( "At what age will the percentage of Americans with heart disease be 70%?<BR>\n" );
document.write( "I'm thinking it works like this:\r<BR>\n" );
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document.write( "                            0.7 = 90/1+271e^-0.122x<BR>\n" );
document.write( "                         ln 0.7= ln (90/1+271e^-0.122x)<BR>\n" );
document.write( "                         NOW I AM STUCK!!!!! WHAT NOW???!!!! THX!!\r<BR>\n" );
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document.write( " </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #268379 by </B><A HREF=/tutors/aboutme.mpl?userid=stanbon><B>stanbon(75887)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=stanbon><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=268379\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> This is the model showing the percentage of Americans with heart disease who are \"x\" years old: <BR>\n" );
document.write( "90/1+271e^-0.122x<BR>\n" );
document.write( "At what age will the percentage of Americans with heart disease be 70%?<BR>\n" );
document.write( "I'm thinking it works like this: <BR>\n" );
document.write( "0.7 = 90/1+271e^-0.122x<BR>\n" );
document.write( "----------------------------<BR>\n" );
document.write( "Try this:<BR>\n" );
document.write( "70 = 90/[1+271e^-0.122x]<BR>\n" );
document.write( "----<BR>\n" );
document.write( "1 + 271e^-0.122x = 90/70 = 1.2857<BR>\n" );
document.write( "---<BR>\n" );
document.write( "271e^-0.122x = 0.2857<BR>\n" );
document.write( "---<BR>\n" );
document.write( "e^-0.122x = 0.004744<BR>\n" );
document.write( "---<BR>\n" );
document.write( "Take the ln to get:<BR>\n" );
document.write( "-0.122x = -5.3508<BR>\n" );
document.write( "---<BR>\n" );
document.write( "x = 43.86 yrs old<BR>\n" );
document.write( "------------------------<BR>\n" );
document.write( "Cheers,<BR>\n" );
document.write( "Stan H. </SPAN>\n" );
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