SOLUTION: An aeroplane takes 30minutes longer to fly 300km against a wind blowing at a constant speed than when flying with the wind. The speed of the aeroplane is 250km/h when no wind is bl

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Question 894928: An aeroplane takes 30minutes longer to fly 300km against a wind blowing at a constant speed than when flying with the wind. The speed of the aeroplane is 250km/h when no wind is blowing
What's the speed of the wind.
Please help.
Thanks.
Answer by lwsshak3(11628) About Me  (Show Source):
You can put this solution on YOUR website!
An aeroplane takes 30minutes longer to fly 300km against a wind blowing at a constant speed than when flying with the wind. The speed of the aeroplane is 250km/h when no wind is blowing
What's the speed of the wind.
***
let c=speed of wind
250+c=speed of plane with wind
250-c=speed of plane against wind
travel time=distance/speed
..
300/(250-c)-300/(250+c)=1/2
lcd:(250-c)(250+c)
300(250+c)-300(250-c)=(1/2)(250-c)(250+c)
75000+300c-75000+300c=(1/2)(62500-c^2)
600c==(1/2)(62500-c^2)
1200c=62500-c^2
c^2+1200c-62500=0
(c+1250)(c-50)=0
c=-1245 (reject)
or
c=50
speed of the wind=50 km/hr