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Question 456698: A plane can travel 640 miles against the wind in the same time it can travel 800 miles with the wind. If the plane can fly 180 mph in calm air, what is the speed of the wind?
I got 20mph... would that be correct? Thanks :)
Answer by bucky(2189)   (Show Source):
You can put this solution on YOUR website! Well, let's just check your answer and see if it is correct.
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We know that the plane can travel 180 miles per hour when no wind is involved. When it flies against the wind, that rate is slowed down by the speed of the wind. Since you say the wind is 20 miles per hour, subtract that from the 180 miles per hour the plane is capable of and you get a true speed of 160 mph for the plane. At 160 mph going against the wind, how long does it take to fly 640 miles. Dividing 640 miles by 160 miles per hour and you find that this trip would take 4 hours.
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When the plane is flying with the wind you add the speed of the wind to the speed that the airplane is capable of in still air to get the true speed. So going with the wind the plane's true speed is 180 mph plus the 20 miles per hour that you think is the wind speed. So with the wind, the plane's true speed is 200 mph. How long would it take the plane at this speed to fly 800 miles? Dividing 800 miles by 200 miles per hour and you find that this trip also takes 4 hours.
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Since plane going against the wind flies 640 miles in 4 hours and going with the wind flies 800 miles in 4 hours if the wind is 20 mph, your answer must be correct.
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Good work!!! Keep it up!
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Hope this helps you to see how you could have checked your answer to see that it was correct.
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