Question

Two train 75 km apart approach each other on parallel tracks, each moving at

15km/h. A bird flies back and forth between the trains at 20km/h until the trains pass
each other. How far does the bird fly?

Answer 1

The bird flies a total distance of 50 km.

Step-by-step explanation:

To find the distance the bird flies, we need to determine the time it takes for the trains to pass each other. Since the trains are 75 km apart and each moving at 15 km/h, they will take 75 km / (15 km/h + 15 km/h) = 2.5 hours to meet. During this time, the bird flies back and forth at 20 km/h. So, the bird's total distance is 20 km/h * 2.5 hours = 50 km.

Answer 2

The correct solution is "37.5 km".

Step-by-step explanation:

Given:

Distance between the trains,

d = 75 km

Speed of each train,

= 15 km/h

The relative speed will be:

=
`15 + (-15)`

=
`30 \ km/h`

The speed of the bird,

V = 15 km/h

Now,

The time taken to meet will be:

`t=(Distance)/(Relative \ speed)`

`=(75)/(30)`

`=2.5 \ h`

hence,

The distance travelled by the bird in 2.5 h will be:

⇒
`D = V t`

`=15* 2.5`

`=37.5 \ km`