Expert: Abe Mantell - 6/6/2009

Question
Flying with the wind, a small plane can fly 600 mi in 3 h.  
Against the wind, the plane can fly the same distance in 4 h.
Find the rate of the plane in calm air and the rate of the
wind.

Answer
Hello Kathleen,

Let x=the rate of the plane in calm air, and y=the rate of the wind

So, using distance=rate*time we get the two equations:

1. (x+y)*3=600 ==> x+y=200
2. (x-y)*4=600 ==> x-y=150

Solving them yields: x=175 and y=25

Thus, the plane travels at 175 MPH  in calm air, the wind is 25 MPH

Abe