document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=153144>Question 153144</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Can someone please explain this to me? I have no idea where to even start! Much appreciated. \r<BR>\n" );
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document.write( "Find an exponential function of the form f(t) = Y 0 bt to model the data. The number of music cassette tapes sold in 1995 was 272.6 million and in 2003 the number sold was 17.2 million. Let x = 0 in 1995.\r<BR>\n" );
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document.write( "a)	Build a model of the form f(t) = Y 0 bt<BR>\n" );
document.write( "b)	Estimate the number of cassettes sold in 2004.<BR>\n" );
document.write( "c)	When will the number of cassette sales drop below 1.5 million?<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 #112650 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=112650\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Find an exponential function of the form f(t) = Yo b^t to model the data. The number of music cassette tapes sold in 1995 was 272.6 million and in 2003 the number sold was 17.2 million. Let x = 0 in 1995. <BR>\n" );
document.write( "a) Build a model of the form f(t) = Yo b^t<BR>\n" );
document.write( "272.6 = Yo b^0<BR>\n" );
document.write( "Therefore Yo = 272.6 million<BR>\n" );
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document.write( "17.2 = 272.6 b^8<BR>\n" );
document.write( "b^8 = 0.063096...<BR>\n" );
document.write( "b = 0.707946...<BR>\n" );
document.write( "EQUATION:<BR>\n" );
document.write( "f(t) = 272.6*0.707946^t<BR>\n" );
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document.write( "b) Estimate the number of cassettes sold in 2004.<BR>\n" );
document.write( "f(9) = 272.6*0.707946^9 = 12.176677 million<BR>\n" );
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document.write( "c) When will the number of cassette sales drop below 1.5 million?<BR>\n" );
document.write( "272.6*0.707946^t < 1.5<BR>\n" );
document.write( "0.707946^t < 0.005503<BR>\n" );
document.write( "t*ln(0.707946)< ln(0.00550)<BR>\n" );
document.write( "t < ln(0.0055)/ln(0.707946)<BR>\n" );
document.write( "t < -5.202540/-0.345387<BR>\n" );
document.write( "t < 15.06<BR>\n" );
document.write( "Ans: 1995 + 15 = 2010<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
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