document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=405646>Question 405646</A>: <I><SPAN STYLE=\"word-break: break-all;\"> a plane flies 400 miles downwind in the same amount of time as it takes to travel 320 miles upwind. of the plane can fly at 360 mph in still air, find the velocity of the wind. </SPAN>\n" );
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document.write( "400=(360+W)T <BR>\n" );
document.write( "T=400/(360+W) FOR THE DOWNWIND FLIGHT.<BR>\n" );
document.write( "320=(360-W)T <BR>\n" );
document.write( "T=320/(360-W) FOR THE UPWIND FLIGHT.<BR>\n" );
document.write( "BECAUSE THE TIMES (T) ARE EQUAL THEN:<BR>\n" );
document.write( "400/(360+W)=320/(360-W)  CROSS MULTIPLY.<BR>\n" );
document.write( "400(360-W)=320(360+T)<BR>\n" );
document.write( "144,000-400W=115,200+320T<BR>\n" );
document.write( "-400W-320W=115,200-122,000<BR>\n" );
document.write( "-720W=-28,800<BR>\n" );
document.write( "W=-28,800/-720 <BR>\n" );
document.write( "W=40 MPH. IS THE WIND SPEED.<BR>\n" );
document.write( "PROOF:<BR>\n" );
document.write( "400/(360+40)=320(360-40)<BR>\n" );
document.write( "400/400=320/320<BR>\n" );
document.write( "1/1=1/1<BR>\n" );
document.write( "1=1\r<BR>\n" );
document.write( "\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );