Problema Solution
A plane traveled 2520 miles to Tahiti and back. The trip was with the wind. It took 15 hours. The trip back was into the wind. The trip back took 21 hours. What is the speed of the plane in still air? What is the speed of the wind?
Answer provided by our tutors
Let
plane speed in still air = x mph
wind speed = y mph
against the wind: speed is x-y while the time is t1 = 21.00 hours
with the wind: speed is x+y while the time is t2 = 15.00 hours
Since distance = speed*time we have:
(x - y)*t1 = 2520
(x + y)*t2 = 2520
That is we have the following system of equations:
(x - y)*21 = 2520
(x + y)*15 = 2520
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click here to see the system of equations solved for x and y
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x = 144 mph
y = 24 mph
The speed of the plane in still air is 144 mph while the speed of the wind is 24 mph.