Aptitude - Problems on Trains - Discussion

Discussion Forum : Problems on Trains - General Questions (Q.No. 8)
8.
A train 360 m long is running at a speed of 45 km/hr. In what time will it pass a bridge 140 m long?
40 sec
42 sec
45 sec
48 sec
Answer: Option
Explanation:

Formula for converting from km/hr to m/s:   X km/hr = X x 5 m/s.
18

Therefore, Speed = 45 x 5 m/sec = 25 m/sec.
18 2

Total distance to be covered = (360 + 140) m = 500 m.

Formula for finding Time = Distance
Speed

Required time = 500 x 2 sec = 40 sec.
25

Discussion:
78 comments Page 8 of 8.

Ankit Shukla said:   1 decade ago
I think total distance is 360+140+360 = 860 m.

Because the length is started from the starting point to end point of the train.

Vishal said:   1 decade ago
Not train is add own length + Pass platform length.

E.g: Train length 345.

Platform 456.

Train length + Platform length.

345+456 = 801.

Now you got it.

Joydeep mukherjee said:   1 decade ago
There are no starting and end point mentioned in the question.

Whenever, you get this type of question, just.

Total length = 360+140 m = 500 m.

Saiteja said:   1 decade ago
Train speed = 45 km/hr.

= 45*(5/18) = 12.5 m/sec.

140 m long bridge cross in = 140/12.5 = 11.2 sec.

Including train length crossing time i.e. 360/12.5 = 28.8 sec.

Total = 11.2+28.8 = 40 sec.

Aditya said:   1 decade ago
From where did 45*(5/18) came please explain?

Prasun jana said:   1 decade ago
Speed = 45*(5/18) = 12.5.

= (360+140)/12.5 = 40.

Chetan said:   1 decade ago
Discussion was very nice it's very clear to all.

Syed khamar said:   1 decade ago
S = 45*5/18 => 25/2.

Now train passes platform = 360+140/25/2.

= 500*2/25.

= 40 sec.


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