what is the rate of the jetstream?

Question

A jet travels
4518mi
against a jetstream in
6
hours and
5058mi
with the jetstream in the same amount of time. What is the rate of the jet in still air and what is the rate of the jetstream?

Answer 1

Use the formula

 

distance = velocity*time

 

d = vt

 

Let u = velocity of jet in still air and w = velocity of jetstream

 

Then from the given information,

 

4518 mi = (u - w)(6 hrs)

5058 mi = (u + w)(6 hrs)

 

(i)   4518 = 6(u - w)

(ii)  5058 = 6(u + w)

 

Add (i) to (ii) to get u:

 

9576 = 12u ⇒ u = 798 mi/hr

 

Substitute u = 798 into either (i) or (ii) and get w.  Using (i),

 

4518 = 6(798 - w) ⇒ w = 45 mi/hr