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 3 of 6.
Sahdev said:
8 years ago
3(800+x) =3900 = 1500.
Then x = 500?
Then x = 500?
Asmamaw said:
8 years ago
How the number 5/18 came? please clarify me.
Jay said:
9 years ago
Speed=78 km/hr
=78 x 5/18 = 65/3 m/sec
Time = i min = 60 sec
Let the length of he tunnel be x metres
but here already given 800 metres
Therefore d=s x t
So,
800x=65/3 x 60
800x= 1300
x= 1300 - 800
x= 500.
=78 x 5/18 = 65/3 m/sec
Time = i min = 60 sec
Let the length of he tunnel be x metres
but here already given 800 metres
Therefore d=s x t
So,
800x=65/3 x 60
800x= 1300
x= 1300 - 800
x= 500.
Dinesh said:
9 years ago
If there will be 75 km/h then what will be the answer?
Karthik said:
10 years ago
How the 5/18 came?
Nik said:
10 years ago
Hi.
Distance/time = Speed.
Let length of the tunnel be x.
Then Distance = Lenth of Train + Lenght of the tunnel.
ie. (800+x)/60 = (65/3).
Now 800 + x = (65/3)*60.
ie 800 + x = 1300.
x = 1300 - 800.
x = 500.
Distance/time = Speed.
Let length of the tunnel be x.
Then Distance = Lenth of Train + Lenght of the tunnel.
ie. (800+x)/60 = (65/3).
Now 800 + x = (65/3)*60.
ie 800 + x = 1300.
x = 1300 - 800.
x = 500.
(1)
Manju said:
1 decade ago
5/18 means?
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.
Parameshwar said:
1 decade ago
May I know, how we got 5/18?
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.
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