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:
52 comments Page 2 of 6.
Manju said:
10 years ago
5/18 means?
Karthik said:
9 years ago
How the 5/18 came?
Jay said:
8 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?
Shivam shah said:
10 years 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.
Sarang said:
7 years ago
Distance =speed * time,
D=78km/h*1minute,
D=78*5/18*60.
D=78*.277*60.
D=21.6*60= 1300-800= 500.
D=78km/h*1minute,
D=78*5/18*60.
D=78*.277*60.
D=21.6*60= 1300-800= 500.
Arushi said:
6 years ago
I am not getting, how come 5/18? Please, someone explain me.
Roobha said:
6 years ago
1km = 1000m,
1hr = 3600sec.
Convert,
Km/hr=m/sec.
= 1000/3600m/sec,
= 5/18m/sec.
1hr = 3600sec.
Convert,
Km/hr=m/sec.
= 1000/3600m/sec,
= 5/18m/sec.
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