document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=98845>Question 98845</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Tutor, \r<BR>\n" );
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document.write( "I only have a couple of problems left that I am having trouble with could you help me with this word problem please?  \r<BR>\n" );
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document.write( "A plane flies 720 mi against a steady 30 mi/h headwind and then returns to the same point with the wind.  If the entire trip takes 10 h, what is the plane's speed in stil air?   </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #71908 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=71908\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> A plane flies 720 mi against a steady 30 mi/h headwind and then returns to the same point with the wind. If the entire trip takes 10 h, what is the plane's speed in stil air? <BR>\n" );
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document.write( "Let plane speed in still air be \"P\".<BR>\n" );
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document.write( "With wind DATA:<BR>\n" );
document.write( "distance = 720 miles; rate = p+30 mph ; time = d/r = 720/(p+30)<BR>\n" );
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document.write( "Against wind DATA;<BR>\n" );
document.write( "distance = 720 miles ; rate = p-30 mph ; time = d/r = 720/(p-30)<BR>\n" );
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document.write( "EQUATION:<BR>\n" );
document.write( "time + time = 10 hrs<BR>\n" );
document.write( "720/(p+30) + 720/(p-30) = 10<BR>\n" );
document.write( "72/(p+30) + 72/(p-30) = 1<BR>\n" );
document.write( "72(p-30) + 72(p+30) = p^2-900<BR>\n" );
document.write( "144p = p^2-900<BR>\n" );
document.write( "p^2-144p-900=0<BR>\n" );
document.write( "(p-150)(p+6)=0<BR>\n" );
document.write( "Positive answer:<BR>\n" );
document.write( "p = 150 mph (plane's speed in still air)<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
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