Roxi R.

asked • 05/02/13

Flying with a tailwind a plane averaged 158 km/h. On the return trip the plane averaged 112 km/h with same wind. Find wind & plane speed in still air.

I got as far as  plane speed + wind  = 158 and plane speed - wind = 112.

But I don't know how to solve the problem.

2 Answers By Expert Tutors

By:

John R. answered • 05/02/13

Tutor
4.6 (55)

John R: Math, Science, and History Teacher

Roxi R.

I used this method on another problem and I'm getting two different answers.

A small jet plane whose speed in still air is 220 km/h can travel 520 km with the wind in the same amount of time as it takes to fly 360 km against the wind. What is the wind speed?

I get (220+ 360)/2 = 70. But if I use John's method.

I get wind speed is 80.

220t +w = 520 and 220t -2 = 360. Using elimination method I get 440t =880

t=2. Then substitute into eq 1 and get 220(2) +w = 520 2 = 80

So which is right?

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05/08/13

Brad M.

tutor

Wind speed is 40 km/h; total trip time 880 km/ 220 km/h=  4hours.

2 hours each leg==> 520/2= 260 km/h with 40 wind boost; 360/2= 180 km/h against same wind of 40 :) 

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05/08/13

Brad M.

tutor

Wind speed is 40 km/h; total trip time 880 km/ 220 km/h=  4hours.

2 hours each leg==> 520/2= 260 km/h with 40 wind boost; 360/2= 180 km/h against same wind of 40 :) 

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05/08/13

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