document.write( "Question 555059: A plane can travel 350 km/h in still air. With the wind it flew 1000 km. In the same amount of time it could travel 750 km against the wind. Find the speed of the wind. \n" ); document.write( "

Algebra.Com's Answer #361666 by ankor@dixie-net.com(22740) $\"\"$ $\"About$

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A plane can travel 350 km/h in still air. With the wind it flew 1000 km.
\n" ); document.write( " In the same amount of time it could travel 750 km against the wind.
\n" ); document.write( " Find the speed of the wind.
\n" ); document.write( ":
\n" ); document.write( "Let w = speed of the wind
\n" ); document.write( "then
\n" ); document.write( "(350-w) = effective speed against the wind
\n" ); document.write( "and
\n" ); document.write( "(350+w) = effective speeed with
\n" ); document.write( ":
\n" ); document.write( "Write a time equation: time = dist/speed
\n" ); document.write( ":
\n" ); document.write( " $\"1000%2F%28%28350%2Bw%29%29\"$ = $\"750%2F%28%28350-w%29%29\"$
\n" ); document.write( "Cross multiply
\n" ); document.write( "1000(350-w) = 750(350+w)
\n" ); document.write( "simplify divide both sides by 250, results
\n" ); document.write( "4(350-w) = 3(350+w)
\n" ); document.write( "1400 - 4w = 1050 + 3w
\n" ); document.write( "1400 - 1050 = 7w + 4w
\n" ); document.write( "350 = 7w
\n" ); document.write( "w = $\"350%2F7\"$
\n" ); document.write( "w = 50 mph is the speed of the wind
\n" ); document.write( ":
\n" ); document.write( ":
\n" ); document.write( "Confirms this find the times of each trip
\n" ); document.write( "1000/400 = 2.5 hrs
\n" ); document.write( "750/300 = 2.5 \n" ); document.write( "

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