distance problem

Question

Because of the jet stream, it takes 8 hours to fly from Orlando to London and 9.5 hours to return. If an airplane averages 550 mph in still air, what is the average rate of the wind blowing in the direction from Orlando to London?

Answer 1

plane speed:  p = 550

rate to London = 550 + s     travelling with jet stream

rate from London = 550-s    travelling against the jet stream

 

d = rt

 

to London:  d = (550+s)8

From London d = (550-s)9.5

 

Since the distance is the same set the two equal to each other

to solve for s, the wind speed of the jet stream

 

8(550+s) = 9.5(550-s)         multiply through parenthesis

8s + 4400 = -9.5s + 5225    add 9.5s to both sides

17.5s + 4400 = 5225           subtract 4400 from both sides

17.5s = 825                        divide both sides by 17.5

s = 825/17.5

s = 47.14 mph

 

The jet stream wind blows at approximately 47.1 mph