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:
252 comments Page 25 of 26.
Ishwarya said:
8 years ago
Shouldn't we are considering from the time the train's front enters the bridge till the tail is completely off the bridge as 30 seconds?
Then it would be 375- (130+130) =115m.
Then it would be 375- (130+130) =115m.
Sasidhar nrit said:
8 years ago
45 km/hr.
45000/60min = 750m /min.
travelling 750m per minute,
750m/30sec = 375m,
than 375m-130m = 245m.
Is this correct?
45000/60min = 750m /min.
travelling 750m per minute,
750m/30sec = 375m,
than 375m-130m = 245m.
Is this correct?
Hashwanth said:
7 years ago
So, guys is this assumption is correct? Please tell me.
Assumption is if I thinking about a total distance, that means, does it include train's distance and the distance it traveled?
Assumption is if I thinking about a total distance, that means, does it include train's distance and the distance it traveled?
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:
7 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:
7 years ago
45 * (5÷18) = (Lb +130)/30.
Lb = 245 m.
Lb = 245 m.
Sejarc said:
7 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.
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