Question

speeds of two train ratio 3:4 .they are going in opposition direction along paraell tracks. if each takes 3 sec to cross a telegraph post.find time ta

Answer 1

Answer:

Both trains will cross each other in 3 sec

Given:

Speeds of two train in ratio 3:4

They are going in opposite direction and each takes 3 sec to cross a telegraph post

To find:

Time taken by both trains to cross each other

Solution:-

Let the speeds be 3x and 4x

Total relative speed=3x+4x

=7x

According to the question both trains takes 3 sec to cross a post

Length of 1st train=3x × 3

=9x

Length of 2nd train=4x ×3

=12x

Total length=9x+12x

=21x

Now we know that

$speed = \frac{distance}{time}$

$time = \frac{distance}{speed}$

$= \frac{21x}{7x}$

$= 3x$

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Both trains cross each other in 3 sec