Question

An airplane takes 3 hours to travel a distance of 1680 miles with the wind. The return trip was 4 hours against wind. Find the speed of the plane in still air and the speed of the wind

Answer 1

Speed of plane in still air: 490 mile/hour

speed of wind: 70 mile/hour

Explanation:

still speed = x wind speed = w

with wind: speed = still + wind

(x+w) * 3 = 1680 ...a

against wind: speed = still - wind

(x-w) * 4 = 1680 ...b

b-a ... 4x-4w-3x-3w = 0

x-7w = 0

x = 7w

substitution: (7w+w)*3 = 1680 8w = 560 wind speed (w) = 70

still speed (x) = 7w = 490 mile/hour