Question

A jet travels 4680 miles against the wind in eight hours and 5720 miles in the wind in the same amount of time what is the rate of the jet in still air and what is the rate of the wind

Answer 1

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Answer:

• jet: 650 mph
• wind: 65 mph

Step-by-step explanation:

The speed against the wind is ...

  4680 mi/(8 h) = 585 mi/h

The speed with the wind is ...

  5720 mi/(8 h) = 715 mi/h

The speed of the airplane in still air is the average of these speeds:

  (585 +715)/2 = 650 mi/h . . . speed in still air

The speed of the wind is the difference between the airplane speed and the speed in the wind:

  715 -650 = 65 mi/h . . . speed of the wind

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Additional comment

If p and 'a' represent the speeds of the plane and the air, the speeds with and against the wind are ...

  p + a = with

  p - a = against

If we average these, we get ...

  ((p +a) +(p -a))/2 = (with + against)/2

  p = (with + against)/2 . . . . . . . the formula we used above