document.write( "Question 969048: a jet plane flying with the wind went 2100 mi in 4 h. Against the wind, the plane could fly only 1760 mi in the same amount of time. Find the rate of the plane in calm air and the rate of the wind. \n" ); document.write( "

Algebra.Com's Answer #592108 by ankor@dixie-net.com(22740) $\"\"$ $\"About$

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a jet plane flying with the wind went 2100 mi in 4 h.
\n" ); document.write( "Against the wind, the plane could fly only 1760 mi in the same amount of time.
\n" ); document.write( " Find the rate of the plane in calm air and the rate of the wind.
\n" ); document.write( ":
\n" ); document.write( "let s = the speed of the plane in still air
\n" ); document.write( "let w = the rate of the wind
\n" ); document.write( "then
\n" ); document.write( "(s+w) = effective speed with the wind
\n" ); document.write( "and
\n" ); document.write( "(s-w) = effective speed against the wind
\n" ); document.write( ":
\n" ); document.write( "Write an distance equation for each way, (dist = time * speed
\n" ); document.write( "4(s+w) = 2100
\n" ); document.write( "4(s-w) = 1760
\n" ); document.write( "simplify both equations by dividing both sides by 4, use elimination
\n" ); document.write( "s + w = 525
\n" ); document.write( "s - w = 440
\n" ); document.write( "-------------Addition will eliminate w, find s
\n" ); document.write( "2s = 965
\n" ); document.write( "s = 965/2
\n" ); document.write( "s = 482.5 mph is the plane speed in still air
\n" ); document.write( "Find w using the first simplified equation
\n" ); document.write( "482.5 + w = 525
\n" ); document.write( "w = 525 - 482.5
\n" ); document.write( "w = 42.5 mph is the rate of the wind
\n" ); document.write( ":
\n" ); document.write( ":
\n" ); document.write( "Confirm this with the 1st original equation
\n" ); document.write( "4(482.5 + 42.5) = 2100
\n" ); document.write( "4(525) = 2100
\n" ); document.write( " \n" ); document.write( "

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