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 4 of 6.
Dinesh said:
9 years ago
If there will be 75 km/h then what will be the answer?
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.
Sahdev said:
8 years ago
3(800+x) =3900 = 1500.
Then x = 500?
Then x = 500?
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?
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.
Sasinrit said:
7 years ago
Speed =78000/3600=1300/min.
Length of tunnel=1300-800=500.
Length of tunnel=1300-800=500.
(1)
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.
Yt prasad said:
6 years ago
65/3 * 60 = 65 * 20 = 1300 - 800 = 500.
(2)
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