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:
250 comments Page 10 of 25.
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.
Raj Kumar said:
2 years ago
My Question is why we should convert 45 km/hr into meters/per second which is a unit of speed instead of that we can convert 130/30 which is also equal to speed?
Anyone, explain this to me.
Anyone, explain this to me.
(10)
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.
Bhavana B Nayak said:
2 years ago
Length of bridge = (speed of the train * time taken to cross the bridge) - length of the train.
= ((45*5/18)*30) - 130,
=((25/2) * 30) -130,
=(750/2) - 130,
= 375m/s - 130s,
= 245m.
= ((45*5/18)*30) - 130,
=((25/2) * 30) -130,
=(750/2) - 130,
= 375m/s - 130s,
= 245m.
(94)
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.
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?
Murugan said:
1 decade ago
@Nithin.
Distance = speed x time.
So distance = 45*5/18*30.
Distance = 375 (this is the length of both train+bridge).
So we have to subtract train length (130 m).
Distance = 245.
Distance = speed x time.
So distance = 45*5/18*30.
Distance = 375 (this is the length of both train+bridge).
So we have to subtract train length (130 m).
Distance = 245.
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.
Parthiban said:
1 decade ago
Easy to find no need to put x and y.
45000m/360seconds = 125 mps.
30 seconds so, crossing bridge.
30*125=375m.
Subtract the train meter : 130m.
Answer : 375-130=245m.
45000m/360seconds = 125 mps.
30 seconds so, crossing bridge.
30*125=375m.
Subtract the train meter : 130m.
Answer : 375-130=245m.
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.
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