Question

An aeroplane flies 1680 km witha head wind in 3.5 hours. on return trip with same wind blowing, the plane takes 3 hours. Find the plane's air speed and the wind speed.

Answer 1

Let the air speed be x km/hr and speed of the wind be y km/hr.

Given, x - y = 1680/3.5

                    = 480    ---------- (1)

Given, x + y = 1680/3

                    = 560   ------------ (2)

On solving (1) and (2) we get

    x - y = 480
    x + y = 560
------------------------
           2x = 1040

             x = 520.

Substitute x = 520 in above equations, we get y = 40.

Plane's airspeed = 520km/hr and wid speed = 40km/hr.


Hope this helps!

Answer 2

Answer:

520 km/h,40 km/h

Step-by-step explanation:

Let’s assume the speed of the plane =x km/hr

And let the speed of wind =y km/hr

So, the speed of the aeroplane in the direction of wind =(x+y)km/hr

Speed of the aeroplane in the opposite direction of wind =(x–y)km/hr

We know that, distance=speed×time

Then according to the given conditions, we have

1680=(x−y)×3.5

⇒x−y=

3.5

1680

⇒x−y=480 … (i)

And,

1680=(x+y)×3

⇒x+y=

3

1680

⇒x+y=560 … (ii)

Adding equation (i) and (ii), we get

2x=1040

⇒x=

2

1040

=520

Substituting the value of x in equation (i), we get

520−y=480

⇒y=520−480

⇒y=40

Therefore, the speed of aeroplane =520 km/hr and the speed of wind =40 km/hr.