document.write( "Question 159809: A 6-passenger plane cruises at 180 mph in calm air. If the plane files 7 miles with the wind in the same smount of time as it flies 5 miles against the wind, then what is the wind speed? \n" ); document.write( "

Algebra.Com's Answer #117921 by ankor@dixie-net.com(22740) $\"\"$ $\"About$

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A 6-passenger plane cruises at 180 mph in calm air. If the plane files 7 miles
\n" ); document.write( " with the wind in the same amount of time as it flies 5 miles against the wind,
\n" ); document.write( " then what is the wind speed?
\n" ); document.write( ":
\n" ); document.write( "Let x = wind speed
\n" ); document.write( "then
\n" ); document.write( "(180+x) = speed with the wind
\n" ); document.write( "and
\n" ); document.write( "(180-x) = speed against
\n" ); document.write( ":
\n" ); document.write( "Write a time equation; time = $\"dist%2Fspeed\"$
\n" ); document.write( ";
\n" ); document.write( "With time = against time
\n" ); document.write( " $\"7%2F%28%28180%2Bx%29%29\"$ = $\"5%2F%28%28180-x%29%29\"$
\n" ); document.write( "Cross multiply
\n" ); document.write( "5(180+x) = 7(180-x)
\n" ); document.write( ":
\n" ); document.write( "900 + 5x = 1260 - 7x
\n" ); document.write( ":
\n" ); document.write( "5x + 7x = 1260 - 900
\n" ); document.write( ":
\n" ); document.write( "12x = 360
\n" ); document.write( "x = $\"360%2F12\"$
\n" ); document.write( "x = 30 mph is speed of the wind
\n" ); document.write( ":
\n" ); document.write( ":
\n" ); document.write( "Check solution, find the times at both speeds 210 mph and 150 mph:
\n" ); document.write( "7/210 = .033 hrs
\n" ); document.write( "5/150 = .033 hrs \n" ); document.write( "

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