A plane can fly 475 miles against the wind in the same amount of time that it can fly 675 miles with the wind. If the wind speed is 40 mph, find the speed of the plane in still air.

230 mph

Step-by-step explanation:

Let speed of plane in still air be x. Therefore, when against the wind speed, the resultant speed is x-40 mph. Equally, when with the wind speed, the resultant speed is x+40 mph. The time is the same hence we can express these as

By cross multiplication

675(x-40)=475(x+40)

675x-27000=475x+19000

200x=46000

X=46000/200=230 mph

9514 1404 393

  The median, because the distribution of wind speeds is skewed.

Step-by-step explanation:

A few higher speeds will raise the mean. For a skewed distribution, the median may be a more appropriate measure of center.

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Additional comment

From an engineering point of view, one might have to consider speeds only within some range, as the wind turbines may be shut down for speeds too low or too high. Likely the power generated is not proportional to speed, so a weighted average (of the square of speed) would probably be more useful. Unfortunately, this question does not get into such subtleties.