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 15 of 25.
Gaurav rana said:
9 years ago
Why 130 is added to it?
Mahi said:
9 years ago
But here, how do you get 5/18?
Janani said:
9 years ago
How get 5/18?
Santosh said:
9 years ago
No, WRONG ANSWER.
The correct answer is 115M.
X + 0.260km = 45 * 30/(60 * 60),
X + 0.26 = 0.375,
=> X= 0.115 KM = 115METERS.
The correct answer is 115M.
X + 0.260km = 45 * 30/(60 * 60),
X + 0.26 = 0.375,
=> X= 0.115 KM = 115METERS.
Sathiyaraj said:
9 years ago
45 km/hr => 45, 000 mts = 3600 sec=>36 s = 450 mts.
Let x be the bridge length.
In 30 sec, trains crosses, 130m + x = 30 sec,
=> (36/6) *5 sec = (450/6) *5 mts,
So, 30 sec = 375 mts,
So, x = 375-130 => x = 245 mts.
Let x be the bridge length.
In 30 sec, trains crosses, 130m + x = 30 sec,
=> (36/6) *5 sec = (450/6) *5 mts,
So, 30 sec = 375 mts,
So, x = 375-130 => x = 245 mts.
Kavya said:
9 years ago
Why are you using '130 + x' ?
Sandhya said:
9 years ago
Can you explain me in detail? I can't understand.
Vinod choudhary said:
9 years ago
Speed = (length of bridge + length of train) /time = (L + l) /t.
45 x (5/18) = (L + 130) /30,
45 x 30 x (5/18) = (L + 130) ,
375 = L + 130,
L = 375 - 130,
L = 245 m.
45 x (5/18) = (L + 130) /30,
45 x 30 x (5/18) = (L + 130) ,
375 = L + 130,
L = 375 - 130,
L = 245 m.
Premasing s rathod said:
9 years ago
Why 18/5?
TFreeN said:
9 years ago
This is very shortcut key.
Simple 45km = 45000 mitr.
1hrs = 3600 sec.
= 45000/3600.
=12.5.
12.5 * 30 second cross.
= 375.
And 375 - 130 mtr.
= 245 mtr.
Simple 45km = 45000 mitr.
1hrs = 3600 sec.
= 45000/3600.
=12.5.
12.5 * 30 second cross.
= 375.
And 375 - 130 mtr.
= 245 mtr.
Post your comments here:
Quick links
Quantitative Aptitude
Verbal (English)
Reasoning
Programming
Interview
Placement Papers