Problema Solution
A plane flies 435 miles with the wind and 345 miles against the wind in the same length of time. If the speed of the wind is 15mph, find the speed of the plane in still air.
Answer provided by our tutors
let
v = the speed of the plane in still air, v>0
w = 15 mph the speed of the wind
traveling with the wind the speed of the plane is: v + w
traveling against the wind the speed of the plane is: v - w
since speed = distance/time follows time = distance/speed
435/(v + w) = 345/(v - w)
435/(v + 15) = 345/(v - 15)
by solving we find:
v = 130 mph
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the speed of the plane in still air is 130 mph.