Question

Flying agaist the wind, an airplane travels 6300 kilometers in7 hours. Flying with the wind, the same plane travels 8400 in 6 hours. What is the rate of the plane is still air and what is the rate of the wind?

Answer 1

• plane: 1150 kph
• wind: 250 kph

Explanation:

The given relationships allow us to write a system of equations in the speeds of the wind and plane.

Let w and p represent the speeds of the wind and the plane, respectively. We know speed is the ratio of distance to time, so ...

p -w = 6300 km/(7 h) = 900 km/h

p +w = 8400 km/(6 h) = 1400 km/h

__

Adding these two equations gives ...

2p = 2300 km/h

p = 1150 km/h . . . . . . divide by 2

Subtracting the first equation from the second gives ...

2w = 500 km/h

w = 250 km/h

The speed of the plane in still air is 1150 km per hour; the speed of the wind is 250 km per hour.