document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=734263>Question 734263</A>: <I><SPAN STYLE=\"word-break: break-all;\"> This question is on inverse variation:<BR>\n" );
document.write( "Tell whether the table represents inverse variation. If so write the inverse variation equation and solve for y when x=40. Show work that supports your conclusions.\r<BR>\n" );
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document.write( "Travel time(x)  speed(y)<BR>\n" );
document.write( "36               50<BR>\n" );
document.write( "50                36<BR>\n" );
document.write( "60                30<BR>\n" );
document.write( "75                24\r<BR>\n" );
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document.write( "I answered yes 36.50\r<BR>\n" );
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document.write( "but y=?(I don't know)what is the equation </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #448886 by </B><A HREF=/tutors/aboutme.mpl?userid=josgarithmetic><B>josgarithmetic(39618)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=josgarithmetic><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=448886\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> y should be related to x according to <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=y=k%2A%281%2Fx%29 ALIGN=MIDDLE  ALT=\"y=k%2A%281%2Fx%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >, if they are in inverse variation.  k is some constant.  That equation is equivalent to <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=xy=k ALIGN=MIDDLE  ALT=\"xy=k\"   DISABLED_style= \"max-width:90%; height:auto;\" >.\r<BR>\n" );
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document.write( "Check to see if this produces a reliable constant, k:\r<BR>\n" );
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document.write( "x_______y_______k=xy<BR>\n" );
document.write( "30______50______1500<BR>\n" );
document.write( "50______36______1800<BR>\n" );
document.write( "60______30______1800<BR>\n" );
document.write( "75______24______1800\r<BR>\n" );
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document.write( "The only data point that does not seem to have the same k value is the first one at x=30; all the rest have k=1800.  The data seem to be reasonably inverse variation if x is great enough, or something beyond 30.  How far below x=50 does k not be constant we do not know.  We do not really have enough data to judge how good is the model at x=40.  May k=1800 fits and maybe it does not fit.  \r<BR>\n" );
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document.write( "If the model fits near or at x=40, then our model, <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=y=1800%2A%281%2Fx%29 ALIGN=MIDDLE  ALT=\"y=1800%2A%281%2Fx%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > gives us:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=y=1800%2A%281%2F40%29 ALIGN=MIDDLE  ALT=\"y=1800%2A%281%2F40%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >=45.  This could only be an ESTIMATE, because, as explained, we do not know how good is our model for values of x below 50.  For the best we have, maybe k is about 1650 at x=40 and maybe <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=y=1650%2A%281%2F40%29 ALIGN=MIDDLE  ALT=\"y=1650%2A%281%2F40%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >=41. </SPAN>\n" );
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