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:
245 comments Page 1 of 25.
Uvitha said:
2 decades ago
Can you explain me in detail ?
Nusrat fathima said:
2 decades ago
I have solved this problem in a different way, is this right way to solve?
speed=25/2 m/sec
length of the bridge be x m
total distance = speed * time
x + 130 = 30 * 25/2
x + 130 = 375
x = 245 m
is the above method to solve this problem right?
Please help.
speed=25/2 m/sec
length of the bridge be x m
total distance = speed * time
x + 130 = 30 * 25/2
x + 130 = 375
x = 245 m
is the above method to solve this problem right?
Please help.
(1)
Nusrat fathima said:
2 decades ago
Hi Uvitha,
Speed=25/2 m/sec
then we find the lenght of the bridge using the formula
distance/time = speed
where distance = length of train + x
Time = 30 sec & speed = 25/2
=> 245 m
Speed=25/2 m/sec
then we find the lenght of the bridge using the formula
distance/time = speed
where distance = length of train + x
Time = 30 sec & speed = 25/2
130 + x 25
------- = --
30 2
=> 245 m
Sai said:
2 decades ago
Hi all, i've solved this problem in anotha way
given,
time=30 sec and speed=45km i.e 45x5/18
so im finding the distance= time x speed = 30 x 225/18 = 375m
thus,the distance travelled by the train is 375m and the length given was 130m
so 375-130 = 245m
Now my question is..could someone insist me that the method followed by me is the right one?
given,
time=30 sec and speed=45km i.e 45x5/18
so im finding the distance= time x speed = 30 x 225/18 = 375m
thus,the distance travelled by the train is 375m and the length given was 130m
so 375-130 = 245m
Now my question is..could someone insist me that the method followed by me is the right one?
Karthik said:
2 decades ago
Yes fathima you are write.
Nusrat Fathima said:
2 decades ago
Thanks karthik
Sai the method mentioned by u is also a right method to solve the above problem..... Good thinking.
Sai the method mentioned by u is also a right method to solve the above problem..... Good thinking.
Jose said:
2 decades ago
Hey how is possible to come ?
2(130 + x) = 750
x = 245 m.
please advice me
2(130 + x) = 750
x = 245 m.
please advice me
Naveen kumar said:
2 decades ago
Hi jose, by cross mulyiplication method it will come as
2(130 + x) = 25*30
then 2(130 + x) = 750
then (130+x)=750/2
then (130+x)=375
then x=375-130
then finally ength of the bridge is 245m.
2(130 + x) = 25*30
then 2(130 + x) = 750
then (130+x)=750/2
then (130+x)=375
then x=375-130
then finally ength of the bridge is 245m.
Nattu said:
2 decades ago
But crossing chould mean the whole train should be off the bridge right? So why should we subtract the length of the train?
Rahul said:
2 decades ago
@deepika @nattu
speed= train length + bridge length
----------------------------
time taken to cross
we know train length, speed and time taken. find out bridge length.
speed= train length + bridge length
----------------------------
time taken to cross
we know train length, speed and time taken. find out bridge length.
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