I got as far as plane speed + wind = 158 and plane speed - wind = 112.
But I don't know how to solve the problem.
I got as far as plane speed + wind = 158 and plane speed - wind = 112.
But I don't know how to solve the problem.
You need to name variables for plane speed and wind speed. For example, I will name them:
x = Plane speed
y = Wind speed
Now you can create two equations in two variables
x + y = 158
x - y =112
This is a good problem for elimination method since you already have one equation with positive y and the other with negative y
x + y = 158
x - y = 112
2x = 270
x = 135
Now substitute the value into either equation to solve for y
x + y - 158
135 + y = 158
y = 23
Hi Roxi -- here's another angle: during a round trip, the wind effect cancels out, much like going downhill and returning uphill. Your "still air" speed would be the average for the round trip = (158+112)/2= 135mph. Therefore, a 23-mph wind boosted the plane to 158 and slowed it to 112. Best regards ma'am ...
Comments
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?
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 :)
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 :)