<PRE><B>Question 268325</B>
With the wind a jet can fly 2500km in 2 hours 30 min.
With wind DATA: 
distance = 2500 km ; time = 2.5 hrs ; rate = 2500/2.5 = 1000 kmh
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Against the wind, it can fly only 2000km in the same time.
Against wind DATA:
distance = 2000 km ; time = 2.5 hrs ; rate = 2000/2.5 = 800 kmh
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The airspeed is the average, 900 kph
The windspeed is the difference, 100 kph
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Airplanes don&#39;t use kilometers and kph, they use nautical miles and knots.
1 knot = 1 nm/hr
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Pilots don&#39;t use &quot;speed in still air&quot;, it&#39;s airspeed.
Airspeed + k*windspeed = ground speed
(k because the wind is not always a direct headwind or tailwind)
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