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:
254 comments Page 12 of 26.
Babool said:
9 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.
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.
Nirmala said:
2 decades ago
Why train length added with bridge length what's the logic behind it?
Why bridge length is not subtracted from train length?
Please clear my doubt.
Why bridge length is not subtracted from train length?
Please clear my doubt.
Vidya said:
1 decade ago
1 hour = 60 min.
1 min = 60 sec.
1 km = 1000 m.
Km per hour to m per sec:
1 km/1 hour = 1000 m/60*60 sec.
=> 1 kmph = 1000/3600 sec = 5/18 sec.
1 min = 60 sec.
1 km = 1000 m.
Km per hour to m per sec:
1 km/1 hour = 1000 m/60*60 sec.
=> 1 kmph = 1000/3600 sec = 5/18 sec.
Jimian said:
2 years ago
Given, train length s = 130.
Let, the bridge length is x.
Total passing length = velocity * time.
S + x = vt.
130 + x = 45 * (5/18) * 30.
x = 245m.
Let, the bridge length is x.
Total passing length = velocity * time.
S + x = vt.
130 + x = 45 * (5/18) * 30.
x = 245m.
(27)
Vikash Kumar Bharti said:
1 year ago
Given, train length s = 130.
Let, the bridge length is x.
Total passing length = velocity * time.
S + x = vt.
130 + x = 45 * (5/18) * 30.
x = 245m.
Let, the bridge length is x.
Total passing length = velocity * time.
S + x = vt.
130 + x = 45 * (5/18) * 30.
x = 245m.
(40)
Chethan said:
1 decade ago
dis=len of train+bridge length(take a bridge as x)
130+x
speed=45km/hr=45*5/18=25/2
time=30sec
dis=speed*time
130+x=25/2*30
130+x=375
x=245m.
130+x
speed=45km/hr=45*5/18=25/2
time=30sec
dis=speed*time
130+x=25/2*30
130+x=375
x=245m.
Prakash said:
4 years ago
Why are you people adding the bridge distance?
If in case the bridge distance is lesser than the train distance, then how it will be calculated?
If in case the bridge distance is lesser than the train distance, then how it will be calculated?
(19)
Nowsath said:
1 decade ago
I have a simple method.
45 * 5/18 equal 12.5 m/s.
Then,
12.5 = x + 130/30 then,
12.5 * 30 = 375.
So,
375 - 130 = 245.
Therefore, x equal 245.
45 * 5/18 equal 12.5 m/s.
Then,
12.5 = x + 130/30 then,
12.5 * 30 = 375.
So,
375 - 130 = 245.
Therefore, x equal 245.
Sanilam Guha said:
5 years ago
(0.130+x) = (45 * 30)/3600.
If assume x is bridge length;
OR, 0.130 + x = 0.375.
OR, X = 0.375 - 0.130.
OR, X = 0.245 KM OR 245 M.
Am I right?
If assume x is bridge length;
OR, 0.130 + x = 0.375.
OR, X = 0.375 - 0.130.
OR, X = 0.245 KM OR 245 M.
Am I right?
(2)
Safina M said:
1 decade ago
Hey Radha,
Cross multiply (139+x)/30=25/2 i.e,
2*(130+x)=30*25.
i.e., 260+2x=750.
2x=750-260.
2x=490.
x=490/2.
Hence, x=245.
Cross multiply (139+x)/30=25/2 i.e,
2*(130+x)=30*25.
i.e., 260+2x=750.
2x=750-260.
2x=490.
x=490/2.
Hence, x=245.
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