Question

a train 270 M long is running by 80 km per hour how much time it will take to cross a tunnel of 360 m

Answer 1

We have given that the train is running with 80 Km/hr, we can write it as 
80,000 m/3,600 sec.

So, 80 Km/hr
means Time taken by train to cover 80 Km = 1 hr,
or                                                     80,000 m = 3600 sec
                                                                  1 m = (3600/80,000) sec
                                                              270 m = (3600x270/80000) sec
                                                                         = (36x27/80) sec
                                                              360 m = (3600x360/80,000) sec
                                                                         = (36x36/80) sec
Since the train is considered to be cross the tunnel when end point of train didn't pass the tunnel, that means train should have to cross the tunnel and then its own length to cross the tunnel.

So, Total time taken by train to cross the tunnel,
                                         [(36x27)+(36x36)]/80
                                     = [927+1296]/80
                                     = 2268/80
                                     = 28.35 sec*

Answer 2

Hello friend

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Given
270m long
360m crossing a tunnel
speed of train = 80km/hr
80*5/18=200/9

distance/speed = 270/200/9
=> 270*9/200 
=12.15 ...... (1)


360/200/9
=>360*9/200
=16.2 ...........(2)

adding 2 and 1

=> 16.2+12.15
= proved 28.35 second

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 i hope it's help u :))