document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=96139>Question 96139</A>This question is from textbook <A HREF=http://www.amazon.com/exec/obidos/ASIN/0534954146/algebrahomeworkh></A><BR>\n" );
document.write( ": <I><SPAN STYLE=\"word-break: break-all;\"> When a popular brand of CD player is priced at $300 per unit, a store sells 15 units per week.Each time the price is reduced by $10, however, the sale increases by two per week. What selling price will result in weekly revenues of $7000?\r<BR>\n" );
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document.write( "Can anyone help me with this? I am not sure about the set up. 300-10x +2 = 7000?<BR>\n" );
document.write( "Thanks </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #69984 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=69984\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> When a popular brand of CD player is priced at $300 per unit, a store sells 15 units per week.Each time the price is reduced by $10, however, the sale increases by two per week. What selling price will result in weekly revenues of $7000?<BR>\n" );
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document.write( "The relation is a linear function: y= mx+b<BR>\n" );
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document.write( "You have two Points: (15,300) (17,290)<BR>\n" );
document.write( "slope = [290-300]/[17-15]= -10/2 = -5<BR>\n" );
document.write( "Pick a point and the slope and solve for the intercept:<BR>\n" );
document.write( "300 = -5*15+b<BR>\n" );
document.write( "b = 375<BR>\n" );
document.write( "EQUATION:<BR>\n" );
document.write( "selling price = -5*(units sold) + 375<BR>\n" );
document.write( "s = -5u + 375<BR>\n" );
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document.write( "Revenue = selling price * # of units<BR>\n" );
document.write( "R = (-5u+375)*u<BR>\n" );
document.write( "R = -5u^2+375u<BR>\n" );
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document.write( "What selling price will result in weekly revenues of $7000? <BR>\n" );
document.write( "7000 = -5u^2+375u<BR>\n" );
document.write( "u^2-75+1400 = 0<BR>\n" );
document.write( "u = [75 +- sqrt(75^2-4*1400)]/2<BR>\n" );
document.write( "u = [75 +- 5]/2<BR>\n" );
document.write( "u = $40 or $35<BR>\n" );
document.write( "When unit price is $40 or $35 Revenue will be $7000<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H.\r<BR>\n" );
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