Aptitude - Problems on Trains - Discussion
Discussion Forum : Problems on Trains - General Questions (Q.No. 17)
17.
A train 800 metres long is running at a speed of 78 km/hr. If it crosses a tunnel in 1 minute, then the length of the tunnel (in meters) is:
Answer: Option
Explanation:
| Speed = |  |
78 x | 5 |  |
m/sec | = | |
65 | |
m/sec. |
| 18 | 3 |
Time = 1 minute = 60 seconds.
Let the length of the tunnel be x metres.
| Then, | |
800 + x | |
= | 65 |
| 60 | 3 |
3(800 + x) = 3900
x = 500.
Discussion:
54 comments Page 6 of 6.
Subhadeep Saha said:
1 decade ago
Why we are converting into seconds we could have converted into meter/minutes, if the train is going in 75km/hr speed means train is going 78000 meters in 60 minutes from here we can execute how much distance the train covers in 1 minutes, after that by subtracting the train length we can execute the tunnel length.
Sandeep kumar said:
1 decade ago
It is simple- as a train covers 78 km in one hour so train covers 78000 meter (78*1000 meter) in 60 minuet, so train cover in one minutes is 78000/60=1300 meter train itself length 800 meter so tunnel length = total distance cover by train-train length, 1300-800 = 500 meter.
Parameshwar said:
1 decade ago
May I know, how we got 5/18?
Shivam shah said:
1 decade ago
Why length is taken as 800 meters here and not 1600? Came to my mind as because when head enters and tail comes out, so length should be considered as 1600.
Post your comments here:
Quick links
Quantitative Aptitude
Verbal (English)
Reasoning
Programming
Interview
Placement Papers