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:
249 comments Page 25 of 25.
Abhi singh said:
7 years ago
So,
45 * 5/18 = 25/2 = 12.5.
Speed = 12.5,
Distance = time * speed = 30 * 12.5 = 375.
130+x = 375,
x = 375-130,
x = 245m/s.
45 * 5/18 = 25/2 = 12.5.
Speed = 12.5,
Distance = time * speed = 30 * 12.5 = 375.
130+x = 375,
x = 375-130,
x = 245m/s.
Mahesh said:
7 years ago
In order to convert a Km/hr to m/sec.
For 1km/hr.
1km=1000m.
1hr=3600sec.
Now 1000/3600=0.277m/sec.
for 45 km/hr.
45km= 45000.
1hr= 3600.
Now 45000/3600=12.5m/sec.
time taken is equal to 30 sec.
Let the length of the bridge be x meters.
Then 130+x/30= 12.5.
= 130+x = 12.5 * 30.
= x = 12.5 * 30-130.
Now x = 245m.
For 1km/hr.
1km=1000m.
1hr=3600sec.
Now 1000/3600=0.277m/sec.
for 45 km/hr.
45km= 45000.
1hr= 3600.
Now 45000/3600=12.5m/sec.
time taken is equal to 30 sec.
Let the length of the bridge be x meters.
Then 130+x/30= 12.5.
= 130+x = 12.5 * 30.
= x = 12.5 * 30-130.
Now x = 245m.
Nilesh said:
7 years ago
How will you get 25/2 from 45 * 5/18?
Saikrishna said:
6 years ago
@Naveen Kumar,
That 2(130+x) = 750 come as,
2(130+x) = 750, then,
Multiply (130+x) with 2 = 260+2x = 750.
260+ 2x = 750 .
2x = 750 - 260.
2x = 490.
x= 490/2.
x= 245 meters.
You got it, this is simple way.
That 2(130+x) = 750 come as,
2(130+x) = 750, then,
Multiply (130+x) with 2 = 260+2x = 750.
260+ 2x = 750 .
2x = 750 - 260.
2x = 490.
x= 490/2.
x= 245 meters.
You got it, this is simple way.
Sathish said:
6 years ago
45 * (5÷18) = (Lb +130)/30.
Lb = 245 m.
Lb = 245 m.
Sejarc said:
6 years ago
It's simple one.
The train goes on a speed of 12.5 m/sec (45km/hr). So it crosses 375m in 30 sec.
Simply, 375 m - length of the train (130 m) =245 m (length of the bridge) => answer.
The train goes on a speed of 12.5 m/sec (45km/hr). So it crosses 375m in 30 sec.
Simply, 375 m - length of the train (130 m) =245 m (length of the bridge) => answer.
Navin said:
6 years ago
How 25/2 came? Explain, please.
Mahamud said:
6 years ago
Can you explain, How come25/2?
Kaushik vinay said:
5 years ago
45*18/5 = 25/3.
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