Question

A plane has an average air speed (this is the speed the plane moves through air) of 750 mph. The plane flies a route of 5000 miles from Los Angeles to London. The average speed of the wind along this route is 30 mph blowing east from Los Angeles towards London. How much longer does it take the plane to fly from London to Los Angeles than the reverse direction?

Answer 1

Answer:

6 hours 15 minutes

Explanation:

On the trip from L.A. to London, the plane travels at 750 mph against a headwind of 50 mph, and that makes the net 700 mph (in aviation speak, 750 is the airspeed, while 700 is the groundspeed).  5000 miles divided by 700 mph results in about 7.14 hours, or about 7 hours and 9 minutes.  On the return trip, ASSUMING THE SAME WIND, the plane travels at 750 mph, but this time the wind of 50 mph is a tail wind.  So the net (groundspeed) is 800 mph.  Traveling 5000 miles at 800 mph only takes 6.25 hours, or 6 hours and 15 minutes.  

Outbound flight 7 hours 9 minutes

Return flight 6 hours 15 minutes