SOLUTION: It took a bird the same amount of time to fly 10 miles with wind as 5 miles against the wind. What is the speed of the wind if the bird flies 30 mph in still air?

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Question 1197131: It took a bird the same amount of time to fly 10 miles with wind as 5 miles against the wind. What is the speed of the wind if the bird flies 30 mph in still air?
Found 2 solutions by Alan3354, ikleyn:
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
It took a bird the same amount of time to fly 10 miles with wind as 5 miles against the wind. What is the speed of the wind if the bird flies 30 mph in still air?
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Airspeed of the bird = 30 mi/hr
w = windspeed
5(30 - w) = 10(30 + w)
30 - w = 60 + 2w
3w = 30
w = 10 mi/hr

Answer by ikleyn(52792) About Me  (Show Source):
You can put this solution on YOUR website!
.

Let w be the rate of the wind.


Write the "time" equation as you read the problem

    10%2F%2830%2Bw%29 = 5%2F%2830-w%29.


Here 30+w is the effective speed with the wind 

and 10%2F%2830%2Bw%29 is the time to fly 10 miles with the wind,

so it explains left side of the equation.



Right side describes the time flying 5 miles against the wind.



From this equation, by cross-multiplying, you get

    10*(30-w) = 5*(30+w)

    300 - 10w = 150 + 5w

    300 - 150 = 10w + 5w

       150    =    15w

         w    =    150/15 = 10 miles per hour.    ANSWER

Solved.