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Aptitude - Problems on Trains - Discussion

Discussion Forum : Problems on Trains - General Questions (Q.No. 3)
Problems on Trains
3.
The length of the bridge, which a train 130 metres long and travelling at 45 km/hr can cross in 30 seconds, is:
200 m
225 m
245 m
250 m
Answer: Option
Explanation:

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

Time = 30 sec.

Let the length of bridge be x metres.

Then, 130 + x = 25
30 2

2(130 + x) = 750

x = 245 m.

Video Explanation: https://youtu.be/M_d8WufJWKc

Discussion:
247 comments Page 18 of 25.
Sumit said:   8 years ago
@Guru.

5/18 is here because to converting distance km/h to m/s it's a formula to convert.
Babool said:   8 years ago
Speed = 45 * 5 m/sec = 25 m/sec.
18 2
Time = 30 sec.

Let the length of the bridge be x metres.

Then, 130 + x = 25.
30 2
2(130 + x) = 750
x = 245 m.
Anil Bhadani said:   8 years ago
45 km *30 sec /3600 sec = 375m.

So length of bridge = passes length - length of train = 375m - 130 m = 245m.
Tejashwini s said:   8 years ago
Good explanation @Anil Bhadani.
Vaibhav mittal said:   8 years ago
Total distance covered by train in crossing the bridge = (25/2) *30=375.

Length of bridge = 375-130 =245.
Surekha said:   8 years ago
How would you say that bridge length would be more that train?

If bridge length is smaller than train means the answer would be vary.
Sid said:   8 years ago
From where 5/18 comes?

Please tell me.
Irene said:   8 years ago
From this formula 2 (130 + x) = 750 ,shouldn't the 2 outside multiple both 130 and x?
I believe it shd be;

160+2x =750,
2x=750-160,
2x=590/2,
x=295m,

2(130+x)=750.
Sowmiya said:   8 years ago
Nice explanation @Coolburn.
Naveen said:   8 years ago
Why you added train length and bridge length?
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