document.write( "Question 331366: Flying against the wind, an airplane travels 5580 in 9 hours. Flying with the wind, the same plane travels 4200 in 5 hours. What is the rate of the plane in still air and what is the rate of the wind? \n" ); document.write( "

Algebra.Com's Answer #237489 by Alan3354(69443) $\"\"$ $\"About$

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Flying against the wind, an airplane travels 5580 in 9 hours. Flying with the wind, the same plane travels 4200 in 5 hours. What is the rate of the plane in still air and what is the rate of the wind?
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\n" ); document.write( "5580 what? Furlongs? Miles? Nautical miles?
\n" ); document.write( "I'll assume nautical miles, since that's what aircraft use.
\n" ); document.write( "5580/9 = 620 knots
\n" ); document.write( "4200/5 = 840 knots
\n" ); document.write( "The airspeed is the average (620+840)/2 = 730 knots
\n" ); document.write( "The \"speed in still air\" is called the airspeed.
\n" ); document.write( "If the people writing the textbooks don't know that, they should not enter problems dealing with it.
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\n" ); document.write( "The wind speed is the difference between airspeed and ground speed
\n" ); document.write( "= 840 - 730
\n" ); document.write( "= 110 knots
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\n" ); document.write( "Aircraft use knots, not mph, for speeds, and so do the weather forecasters.
\n" ); document.write( "1 knot = 1 nautical mile per hour
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