Question

Flying against the jetstream, a jet travels 7380 miles in 9 hours. Flying with the jetstream, the same jet travels 9920 miles in 8 hours. What is the rate of the jet in still air and what is the rate of the jetstream?

Answer 1

The rate of the jet in still air = 1030 miles per hour

And 210 miles per hour is the rate of the stream.

Explanation:

Let the speed of the jet in still air be
`x` miles per hour.

And,the speed of the jetstream be
`y` miles per hour.

Key:So when it is moving against the stream speed will be
`(x-y)` and when it is moving with the stream, speed will be
`(x+y)`

And we know that.

Distance=Speed multiplied with time.

Arranging the equation.

`9920=8 * (x+y)`...equation 1

`7380=9 * (x-y)`...equation 2

Working with the equation by using elimination method.

Dividing equation 1 with 8 and equation 2 with 9.We will have

1240=
`(x+y)`...eqn 3

820=
`(x-y)`...eqn 4

Now adding both the equation will decimate y.

1240+820=2
`x`

2060=2
`x`

Dividing with 2 both sides.

1030=
`x`

By plugging the value of
`x` we can find y in equation 3.

1240=1030 +
`y`

Subtracting 1030 from both sides.

1240-1030=
`y`

`y` =210 miles per hour

So the rate of the jet in still air = 1030 miles per hour

And 210 miles per hour is the rate of the jet stream.