document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=701268>Question 701268</A>: <I><SPAN STYLE=\"word-break: break-all;\"> The quantity demanded for a certain brand of portable CD players is 200 units when the unit price is set at $90. The quantity demanded is 1200 units when the unit price is $40. Find the demand equation and sketch its graph. THANKS </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #432376 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=432376\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> The quantity demanded for a certain brand of portable CD players is 200 units when the unit price is set at $90. The quantity demanded is 1200 units when the unit price is $40. Find the demand equation and sketch its graph. <BR>\n" );
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document.write( "You have two points: (90,200) ; (40,1200)<BR>\n" );
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document.write( "slope = (1200-200)/(40-90) = -1000/50 = -20<BR>\n" );
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document.write( "D(x) = -20x + b<BR>\n" );
document.write( "Solve for \"b\":<BR>\n" );
document.write( "200 = -20*90 + b<BR>\n" );
document.write( "b = 200 + 1800<BR>\n" );
document.write( "b = 2000<BR>\n" );
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document.write( "Equation:<BR>\n" );
document.write( "D(x) = -20x + 2000 where x is the price per unit.<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
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