document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=894928>Question 894928</A>: <I><SPAN STYLE=\"word-break: break-all;\"> An aeroplane takes 30minutes longer to fly 300km against a wind blowing at a constant speed than when flying with the wind. The speed of the aeroplane is 250km/h when no wind is blowing\r<BR>\n" );
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document.write( "What's the speed of the wind.\r<BR>\n" );
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document.write( "Please help.\r<BR>\n" );
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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 #542516 by </B><A HREF=/tutors/aboutme.mpl?userid=lwsshak3><B>lwsshak3(11628)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=lwsshak3><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=542516\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> An aeroplane takes 30minutes longer to fly 300km against a wind blowing at a constant speed than when flying with the wind. The speed of the aeroplane is 250km/h when no wind is blowing<BR>\n" );
document.write( "What's the speed of the wind. <BR>\n" );
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document.write( "let c=speed of wind<BR>\n" );
document.write( "250+c=speed of plane with wind<BR>\n" );
document.write( "250-c=speed of plane against wind<BR>\n" );
document.write( "travel time=distance/speed<BR>\n" );
document.write( "..<BR>\n" );
document.write( "300/(250-c)-300/(250+c)=1/2<BR>\n" );
document.write( "lcd:(250-c)(250+c)<BR>\n" );
document.write( "300(250+c)-300(250-c)=(1/2)(250-c)(250+c)<BR>\n" );
document.write( "75000+300c-75000+300c=(1/2)(62500-c^2)<BR>\n" );
document.write( "600c==(1/2)(62500-c^2)<BR>\n" );
document.write( "1200c=62500-c^2<BR>\n" );
document.write( "c^2+1200c-62500=0<BR>\n" );
document.write( "(c+1250)(c-50)=0<BR>\n" );
document.write( "c=-1245 (reject)<BR>\n" );
document.write( "or<BR>\n" );
document.write( "c=50<BR>\n" );
document.write( "speed of the wind=50 km/hr </SPAN>\n" );
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