document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=436704>Question 436704</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A plane flies 1500 miles against the wind in 3 hours and 45 minutes. The return trip with the wind takes 3 hours. Assume that the wind speed stays constant. Find the speed of the wind and the speed of the airplane with no wind. </SPAN>\n" );
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document.write( "Against the wind, the plane travels the 1500 miles in 3 hours and 45 minutes, or 3 3/4 = 15/4 hours. Its speed is 1500/(15/4) = 400 mph.<br><BR>\n" );
document.write( "With the wind, it travels the 1500 miles in 3 hours; its speed is 1500/3 = 500 mph.<br><BR>\n" );
document.write( "You can of course find the speed of the plane and the speed of the wind using formal algebra.  But common sense and simple mental arithmetic lead quickly to the solution.<br><BR>\n" );
document.write( "Adding the speed of the wind to the speed of the plane gives a speed of 500 mph; subtracting the speed of the wind from the speed of the plane gives a speed of 400 mph.<br><BR>\n" );
document.write( "That means the speed of the plane is halfway between those two speeds, which is 450 mph; and that means the speed of the wind is 50 mph.<br><BR>\n" );
document.write( "ANSWERS: plane speed 450 mph, wind speed 50 mph<br><BR>\n" );
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