Aptitude - Problems on Trains - Discussion
Discussion Forum : Problems on Trains - General Questions (Q.No. 3)
3.
The length of the bridge, which a train 130 metres long and travelling at 45 km/hr can cross in 30 seconds, is:
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.
Thamilarasan said:
1 decade ago
Have any common formulas for easily learning?
Sanjay said:
1 decade ago
B.L. = Bridge Length.
For crossing the bridge distance should be 130+ (B.L) +130.
Then why you are taking 130 + B.L?
For crossing the bridge distance should be 130+ (B.L) +130.
Then why you are taking 130 + B.L?
Sunil Kumar said:
1 decade ago
Let bridge length x m then.
Length of train = 130.
Speed 45*5/18 = 12.5.
Distance=12.5*30 = 375.0-130 = 245.
Length of train = 130.
Speed 45*5/18 = 12.5.
Distance=12.5*30 = 375.0-130 = 245.
Dileep kumar said:
1 decade ago
Distance = speed/time;
Let us bridge length = x say, train travelling distance = 130 m.
The total distance is = x+130;
Speed = 25/2;time = 30sec;
:: x+130 = (25/2) 30;
x = 375-130;
= 245.
Let us bridge length = x say, train travelling distance = 130 m.
The total distance is = x+130;
Speed = 25/2;time = 30sec;
:: x+130 = (25/2) 30;
x = 375-130;
= 245.
Ananth G said:
1 decade ago
@Rohit,
Length=(speed*time).
What you know take left side others stay right side, listen down.
Length
------- = speed {(130+X)/30=25/2,
Time
Than you workout cross multiply method then you get 245m.
Length=(speed*time).
What you know take left side others stay right side, listen down.
Length
------- = speed {(130+X)/30=25/2,
Time
Than you workout cross multiply method then you get 245m.
Rohit said:
1 decade ago
Please help me,
When the train crosses the bridge, shouldn't we consider the length of the train after the bridge also.
All above solutions are only by considering the start point of the train.
And if only that is considered then what is the use of the length of the train.
When the train crosses the bridge, shouldn't we consider the length of the train after the bridge also.
All above solutions are only by considering the start point of the train.
And if only that is considered then what is the use of the length of the train.
Monika said:
1 decade ago
You can do this without any variable:
45 km/hr*5/18 = 25/2 m/s.
Total distance = 25/2*30 = 375.
Length of bridge = 375-130 = 245m.
45 km/hr*5/18 = 25/2 m/s.
Total distance = 25/2*30 = 375.
Length of bridge = 375-130 = 245m.
Srikant kumar said:
1 decade ago
Best Answer could be for new person:
3600 sec me 45000 meter.
1 sec me 45000/3600 12.5 meter/sec.
30 sec me 12.5*30 = 375 meter.
Train length is 130 meter .
Bridge length will be :-375-130 = 245 meter.
3600 sec me 45000 meter.
1 sec me 45000/3600 12.5 meter/sec.
30 sec me 12.5*30 = 375 meter.
Train length is 130 meter .
Bridge length will be :-375-130 = 245 meter.
Parthiban said:
1 decade ago
Easy to find no need to put x and y.
45000m/360seconds = 125 mps.
30 seconds so, crossing bridge.
30*125=375m.
Subtract the train meter : 130m.
Answer : 375-130=245m.
45000m/360seconds = 125 mps.
30 seconds so, crossing bridge.
30*125=375m.
Subtract the train meter : 130m.
Answer : 375-130=245m.
Shoeb said:
1 decade ago
Formula :- Distance=Speed/Time
Answer's in option are given in meter, that mean we can go for 5/18 ready made formula of converting km/hr to m/sec.
* 45 x 5/18 = 12.5 (for 1 second )
* 12.5(sec) x 30(sec)given = 375
* 375-130 (given )= 245.
Answer's in option are given in meter, that mean we can go for 5/18 ready made formula of converting km/hr to m/sec.
* 45 x 5/18 = 12.5 (for 1 second )
* 12.5(sec) x 30(sec)given = 375
* 375-130 (given )= 245.
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