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.
Sampanna said:
1 decade ago
From where did that 5 upon 18 came.
Romon said:
1 decade ago
Train travels @78kmph.
So in 1 minute it goes 78km/60min = 1.3 km per minute or 1300mtr.
Then length of tunnel = (Total length - Length of the Train).
= 1300mtr - 800mtr.
= 500.
So in 1 minute it goes 78km/60min = 1.3 km per minute or 1300mtr.
Then length of tunnel = (Total length - Length of the Train).
= 1300mtr - 800mtr.
= 500.
Ravitheja said:
1 decade ago
Speed of Train = 78kmph.
Speed of Train in Meters/Min =78000/60 = 1300 mpm.
Length of the tunnel be x, Speed = x+800 m/1 min.
There fore calculating for x, x+800/1 = 1300/1 = x = 500 m.
Speed of Train in Meters/Min =78000/60 = 1300 mpm.
Length of the tunnel be x, Speed = x+800 m/1 min.
There fore calculating for x, x+800/1 = 1300/1 = x = 500 m.
John said:
1 decade ago
Can I know from where did 5/18 came?
Izaan prince said:
1 decade ago
Let the speed of tunnel is x.
Length of train is = 800m
Speed of train is = 78km/hr.
Speed in m/s = 78*5/18
Time of crossing tunnel is 1min.
1 min is 60s.
We are finding the length of tunnel = ?
800+x = 78*5/18*60
x = 500
Length of train is = 800m
Speed of train is = 78km/hr.
Speed in m/s = 78*5/18
Time of crossing tunnel is 1min.
1 min is 60s.
We are finding the length of tunnel = ?
800+x = 78*5/18*60
x = 500
Harish said:
1 decade ago
@Pradnyashree.
If we do 3(800+x) = 60*65,
3*800+3x = 3900,
2400+3x = 3900,
3x = 3900-2400,
3x = 500.
x = 166.66 you are wrong.
Here 3x = 3900-2400 = 1500.
x = 500.
If we do 3(800+x) = 60*65,
3*800+3x = 3900,
2400+3x = 3900,
3x = 3900-2400,
3x = 500.
x = 166.66 you are wrong.
Here 3x = 3900-2400 = 1500.
x = 500.
Smith said:
1 decade ago
Train speed 7800m/60m = 1300m.
Length of tunnel is 1300-800 = 500.
Its very simple.
Length of tunnel is 1300-800 = 500.
Its very simple.
Ramya said:
1 decade ago
78 is in kmph but answer is in meter so we should convert km to meter by 5/18 is the formula.
If you want to convert meter into km by 18/5.
If you want to convert meter into km by 18/5.
Sumana said:
1 decade ago
Why we convert 78 meter into seconds?
Anusha said:
1 decade ago
@Kannika
We are adding train length to the tunnel length, because we have to consider the total length so we have to take this.
We are adding train length to the tunnel length, because we have to consider the total length so we have to take this.
Post your comments here:
Quick links
Quantitative Aptitude
Verbal (English)
Reasoning
Programming
Interview
Placement Papers