Q: A plane flies at a speed of 800 miles per hour in still air. It takes 15 minutes longer to fly 1260 mils into the wind than it takes to fly 1320 with the wind. Find the speed of the wind
A: Let the speed of the wind be v miles/h
t be the time in hour that the plane needs to fly 1320 with the wind
By Speed = Distance / Time
(800+v) = 1320/ t ..........(1)
(800-v) = 1260/ (t+1/4).........(2)
(1)+(2), then simplification gives a quadratic equation in t
160t^2-218t-33 = 0
t=1.5, -0.1375(rejected)
So sub into (1) gives v =80
