document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=515003>Question 515003</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Suppose you have a cookie stand, and when you charge $3 per cookie box you sell 250 boxes. But when you raise your price to $4 you only sell 120 boxes. \r<BR>\n" );
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document.write( "a.   Write an equation for the number of boxes you sell as a function of the price you charge. \r<BR>\n" );
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document.write( "b.   Denote \"B\" for number of boxes, and \"P\" for the price you charge.\r<BR>\n" );
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document.write( "c.   Assume the function is linear </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #343668 by </B><A HREF=/tutors/aboutme.mpl?userid=josmiceli><B>josmiceli(19441)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=josmiceli><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=josmiceli><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=343668\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Let <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=B ALIGN=MIDDLE  ALT=\"B\"   DISABLED_style= \"max-width:90%; height:auto;\" > = number of boxes<BR>\n" );
document.write( "Let <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=P ALIGN=MIDDLE  ALT=\"P\"   DISABLED_style= \"max-width:90%; height:auto;\" > = price charged<BR>\n" );
document.write( "Assume a straight line<BR>\n" );
document.write( "The data given tells what the slope of the line is.<BR>\n" );
document.write( "Plot <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=P ALIGN=MIDDLE  ALT=\"P\"   DISABLED_style= \"max-width:90%; height:auto;\" > on the vertical axis<BR>\n" );
document.write( "Plot <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=B ALIGN=MIDDLE  ALT=\"B\"   DISABLED_style= \"max-width:90%; height:auto;\" > on the horizontal axis<BR>\n" );
document.write( "slope = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+%284+-+3%29+%2F+%28+120+-+250+%29+ ALIGN=MIDDLE  ALT=\"+%284+-+3%29+%2F+%28+120+-+250+%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "slope = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+-1%2F130+ ALIGN=MIDDLE  ALT=\"+-1%2F130+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "The equation so far is:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+P+=+-1%2F130%2AB+%2B+P%5B0%5D+ ALIGN=MIDDLE  ALT=\"+P+=+-1%2F130%2AB+%2B+P%5B0%5D+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Where <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+P%5B0%5D+ ALIGN=MIDDLE  ALT=\"+P%5B0%5D+\"   DISABLED_style= \"max-width:90%; height:auto;\" > is the vertical intercept<BR>\n" );
document.write( "Plugging in data:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+-1%2F130+=+-.0077+ ALIGN=MIDDLE  ALT=\"+-1%2F130+=+-.0077+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+3+=+-1%2F130%2A250+%2B+P%5B0%5D+ ALIGN=MIDDLE  ALT=\"+3+=+-1%2F130%2A250+%2B+P%5B0%5D+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+P%5B0%5D+=+3+%2B+1.923+ ALIGN=MIDDLE  ALT=\"+P%5B0%5D+=+3+%2B+1.923+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+P%5B0%5D+=+4.923+ ALIGN=MIDDLE  ALT=\"+P%5B0%5D+=+4.923+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "The equation is:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+P+=+-.0077B+%2B+4.923+ ALIGN=MIDDLE  ALT=\"+P+=+-.0077B+%2B+4.923+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "check answer:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+4+=+-.0077%2A120+%2B+4.923+ ALIGN=MIDDLE  ALT=\"+4+=+-.0077%2A120+%2B+4.923+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+4+=+-.924+%2B+4.923+ ALIGN=MIDDLE  ALT=\"+4+=+-.924+%2B+4.923+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+4+=+3.999+ ALIGN=MIDDLE  ALT=\"+4+=+3.999+\"   DISABLED_style= \"max-width:90%; height:auto;\" > ( error due to rounding off)<BR>\n" );
document.write( "and<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+3+=+-.0077%2A250+%2B+4.923+ ALIGN=MIDDLE  ALT=\"+3+=+-.0077%2A250+%2B+4.923+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+3+=+-1.925+%2B+4.923+ ALIGN=MIDDLE  ALT=\"+3+=+-1.925+%2B+4.923+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+3+=+2.998+ ALIGN=MIDDLE  ALT=\"+3+=+2.998+\"   DISABLED_style= \"max-width:90%; height:auto;\" > ( also round-off error )<BR>\n" );
document.write( "Here's the plot:<BR>\n" );
document.write( " <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+graph%28+400%2C+400%2C+-50%2C+700%2C+-1%2C+6%2C+-.0077x+%2B+4.923+%29+ ALIGN=MIDDLE  ALT=\"+graph%28+400%2C+400%2C+-50%2C+700%2C+-1%2C+6%2C+-.0077x+%2B+4.923+%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" > </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );