Aptitude - Problems on Trains - Discussion
Discussion Forum : Problems on Trains - General Questions (Q.No. 26)
26.
Two trains are running at 40 km/hr and 20 km/hr respectively in the same direction. Fast train completely passes a man sitting in the slower train in 5 seconds. What is the length of the fast train?
Answer: Option
Explanation:
| Relative speed = (40 - 20) km/hr = |  |
20 x | 5 |  |
m/sec = | |
50 | |
m/sec. |
| 18 | 9 |
 Length of faster train = |
|
50 | x 5 | |
m = | 250 | m = 27 | 7 | m. |
| 9 | 9 | 9 |
Discussion:
72 comments Page 3 of 8.
G Rajesh said:
6 years ago
I think if they asked to find the length of the smaller train we have to use same formula as explained above in explaination box. We can assume that length of two trains are same.
Raja.k said:
1 decade ago
@Swetha.
According to this question two trains are in same starting points only but the speed of the two trains is varying. So, anyway we subtract this. Did you understand now.
According to this question two trains are in same starting points only but the speed of the two trains is varying. So, anyway we subtract this. Did you understand now.
Mancy said:
1 decade ago
Hi @Shweta.
We are taking relative speed because in the question direction of moving trains are mentioned so for calculating the length firstly we've to take relative speed.
We are taking relative speed because in the question direction of moving trains are mentioned so for calculating the length firstly we've to take relative speed.
J_k said:
1 decade ago
@Shweta.
If the train is travelling in same direction then we have to add both the speeds, if the train is travelling in opp. direction then we have to subtract them.
If the train is travelling in same direction then we have to add both the speeds, if the train is travelling in opp. direction then we have to subtract them.
Subha said:
1 decade ago
According to the formula given here we can find the SUM OF LENGTH OF THE 2 TRAINS and not the length of the faster train which is asked in the question.
Ram said:
1 decade ago
Just ignore second train(ie., slow train) and assume man is running with 20km/hr speed. Both are in same direction.
Relative speed = 40-20 = 20 kmph.
Relative speed = 40-20 = 20 kmph.
Gaurav said:
1 decade ago
As the man is sitting in the train, he has the same speed as of train, so it simply means that the faster train crosses the slower train in 5 seconds.
Divyansh said:
1 decade ago
When the question says this type that man is sitting but not tells the exact position the apply simple formula speed(Relative) = Distance/Time.
Manasa said:
1 decade ago
What arun said was correct. You consider that man as reference point. Then we can get length of the faster train.
Thank you ARUN.
Thank you ARUN.
Shanmu said:
1 decade ago
We are calculating only the fastest train length know. So where ever the man is sitting the trains length will not vary know guys.
Post your comments here:
Quick links
Quantitative Aptitude
Verbal (English)
Reasoning
Programming
Interview
Placement Papers