Problema Solution

A turboprop plane flying with the wind flew 720 mi in 3 h. Flying against the wind, the plane required 4 h to travel the same distance. Find the rate of the wind and the rate of the plane in calm air.

Answer provided by our tutors

let


w = the rate of the wind


v = the rate of the plane in calm air


d = 720 mi


t1 = 3 h


t2 = 4 h


since distance = speed*time we have


Flying with the wind the speed of the plane is: v + w


v + w = 720/3


v + w = 240


Flying against the wind the speed of the plane is: v - w


v - w = 720/4


v - w = 180


by solving the system of equations:


v + w = 240


v - w = 180


we find:


v = 210 mph


w = 30 mph


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the rate of the wind is 30 mph/


the rate of the plane in calm air is 210 mph.