SOLUTION: A plane has a speed of 840 km/h in still air. It can travel 3120 km with the wind in the same time it would take to travel 1920 km against the wind. Find the speed of the wind.

Question 451983: A plane has a speed of 840 km/h in still air. It can travel 3120 km with the wind in the same time it would take to travel 1920 km against the wind. Find the speed of the wind.
Answer by lwsshak3(11628) (Show Source): You can put this solution on YOUR website!
A plane has a speed of 840 km/h in still air. It can travel 3120 km with the wind in the same time it would take to travel 1920 km against the wind. Find the speed of the wind.
..
let x=speed of wind
(840+x)=speed of plane with wind
(840-x)=speed of plane against wind
Travel time = distance/speed (same with and against the wind)
3120/(840+x)=1920/(840-x)
cross-multiply
3120*840-3120x=1920*840+1920x
3120*840-1920*840=1920x+3120x
5040x=1008000
x=200 km/hr
ans:
Speed of wind=200 km/hr
comment: This is a pretty strong wind speed, but I have doubled check my answer and this is what I got
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