Question

Train A crosses a stationary Train B in 50 seconds and a pole in 20 seconds with the same speed. The length of the<br />
Train A is 240 metres. What is the length of the stationary Train B?<br />
1) 360 metres 2) 260 metres 3) 300 metres<br />
4) Cannot be determined 5) None of these​

Answer 1

Non of these

Step-by-step explanation:

Given:

Train A crosses a stationary Train B in 50 sec.

Train A crosses a pole in 20 sec.

Speed is same in both case.

To find:

Lenght of train B

Point To be remembered

1)Crossing a pole means travelling own lenght.

2) $\sf Speed(s)= \dfrac{Distance(x)}{Time(t)}$

How to find:

First we will find the speed of train by using above formula then we will find the required length.

Solution:

t = 20 sec

x = 240 m [from 1]

s = ?

As we know,

$\sf s= \dfrac{x}{t} \\ \sf \: s = \dfrac{240}{20}\\ \sf s=12$

Now,

s = 12 m/sec

t = 50 sec

x = ?

Again,

$\sf \: x \:= s \times t \\ \sf = 12 \times 50 \\ = 600 \: m$

The required length of Train B is 600 m and our final answer is non of these.

Answer 2

Answer:

a) 360 m

Step-by-step explanation:

Given that, a train crosses a stationary train B in 50 seconds and a pole in 20 seconds with the same speed. The length of the tain A is 240 metres.

We have to find the length of the stationary train B.

Now,

Speed = Distance/Time

Speed = 240/20

Speed = 12 m/s

Therefore, the speed of the train A is 12 m/s.

So, the distance covered by A in 50 sec = speed × time

= 12 × 50

= 600 m

As per given condition we have to find the length of the train B.

So,

Length of train B = Distance covered by A in 50 sec - Length of train A

Substitute the values,

= 600 - 240

= 360

Hence, the length of the train B is 360 m.