SOLUTION: An airplane travels west at 180 km/h, and returns east with the jet stream at 300 km/h. What was the average speed in km/h for the whole trip?

Question 1132034: An airplane travels west at 180 km/h, and returns east with the jet stream at 300 km/h. What was the average speed in km/h for the whole trip?
Found 2 solutions by Alan3354, greenestamps:
Answer by Alan3354(69443) (Show Source): You can put this solution on YOUR website!
An airplane travels west at 180 km/h, and returns east with the jet stream at 300 km/h. What was the average speed in km/h for the whole trip?
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If the distances are the same,
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The avg is 2*180*300/(180+300)
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If the distances are not the same, more info is needed.
Another example of a poorly posed problem.
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PS Airplanes do not use km/hr, they use knots.
1 knot is 1 nautical mile per hour.
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Also, all communications between aircraft and ATC, towers and ground control can be done in English, anywhere in the world.

Answer by greenestamps(13200) (Show Source): You can put this solution on YOUR website!

Let d be the distance for each leg of the trip. Then the total time for the trip is

The total distance is 2d; the average speed is total distance divided by total time:

Simplified, that is 225 km/h.

Note the expression could have been simplified along the way; I kept it in this form so you could see where the formula cited by the other tutor came from.

ANSWER: the average speed is 225 km/h.

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Here is a different way I like to use for solving a problem like this.

The ratio of the two speeds is 180:300 = 3:5. Since the distances are the same, that means the ratio of the times is 5:3.

So for 5/8 of the time the plane is flying at 180 km/h, and for 3/8 of the time it is flying at 300 km/h. The average speed is then

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