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 2 of 6.
Agggy said:
8 months ago
Why we are adding the length of train and length of tunnel? Anyone please explain to me.
(1)
Uday said:
2 decades ago
I do not understand what is the meaning of crossing a tunnel you understand. I think it should mean the moment train head enters the tunnel till its TAIL comes out one can not consider the train is out of tunnel if its head just come out.
(1)
Ralive Faridos said:
4 weeks ago
How to solve this? please explain to me.
Khushi said:
4 years ago
@All.
Please correct me, if my calculation is wrong.
If we convert 78 km/hr into m/s.
So,
78 * 5/18.
390/18.
21.6 m/s.
Now if we put these value.
x + 800/60=21.6,
x + 800= 60 * 21.6,
x+800= 1296,
x= 1296 - 800.
x= 496.
Anyone please clarify this and explain with the correct answer.
Please correct me, if my calculation is wrong.
If we convert 78 km/hr into m/s.
So,
78 * 5/18.
390/18.
21.6 m/s.
Now if we put these value.
x + 800/60=21.6,
x + 800= 60 * 21.6,
x+800= 1296,
x= 1296 - 800.
x= 496.
Anyone please clarify this and explain with the correct answer.
Karthik said:
10 years ago
How the 5/18 came?
Dinesh said:
9 years ago
If there will be 75 km/h then what will be the answer?
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.
Asmamaw said:
8 years ago
How the number 5/18 came? please clarify me.
Naman said:
8 years ago
What if we turn the speed into m/s first, like.
78 x (5/18)=> 65/3 => 15,
then use formula D = S*T.
then we get,
D+800 = 15 * 60.
D+800 = 900,
D = 100,
Is this wrong ?
why 2 different answer?
78 x (5/18)=> 65/3 => 15,
then use formula D = S*T.
then we get,
D+800 = 15 * 60.
D+800 = 900,
D = 100,
Is this wrong ?
why 2 different answer?
Sahdev said:
8 years ago
3(800+x) =3900 = 1500.
Then x = 500?
Then x = 500?
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