Aptitude - Problems on Trains - Discussion
Discussion Forum : Problems on Trains - General Questions (Q.No. 20)
20.
A train moves past a telegraph post and a bridge 264 m long in 8 seconds and 20 seconds respectively. What is the speed of the train?
Answer: Option
Explanation:
Let the length of the train be x metres and its speed by y m/sec.
| Then, | x | = 8  x = 8y |
| y |
| Now, | x + 264 | = y |
| 20 |
8y + 264 = 20y
y = 22.
 Speed = 22 m/sec = |
 |
22 x | 18 |  |
km/hr = 79.2 km/hr. |
| 5 |
Discussion:
46 comments Page 2 of 5.
Mahesh said:
1 decade ago
You see the question he said total is 20 sec.
In that, The train take 8sec to rich post and remaining time is used to cross the bridge.
i.e., 20-8=12.
So 264/12=22.
And 22* (18/5) =79.2km/hr.
In that, The train take 8sec to rich post and remaining time is used to cross the bridge.
i.e., 20-8=12.
So 264/12=22.
And 22* (18/5) =79.2km/hr.
Aarthy said:
8 years ago
@Hussaian.
To convert m/s to km/be, we have the formula a* 18/5 because to convert the metre per sec to km/h we multiply the number to b converted by 3600/1000 by simplifying this we get 18/5.
To convert m/s to km/be, we have the formula a* 18/5 because to convert the metre per sec to km/h we multiply the number to b converted by 3600/1000 by simplifying this we get 18/5.
Krish said:
1 decade ago
S = x/8 m/s.
S = d/t.
x/8 = (264+x)/20.
Solve it and you will get:
x = 176 m.
S = 176/8 = 22 m/s.
Now convert m/s to km/hr.
22*(18/5) = 79.2 km/hr.
That's it.
S = d/t.
x/8 = (264+x)/20.
Solve it and you will get:
x = 176 m.
S = 176/8 = 22 m/s.
Now convert m/s to km/hr.
22*(18/5) = 79.2 km/hr.
That's it.
Janaka said:
1 decade ago
In question No. 19 x/y=15 is mentioned as x/15=y. But in this question when x/y=8 is mentiond as x=8y. What is the reason for this? please explain me.
Divyang said:
1 decade ago
Above in ans x and y are unknown..so that simplify very easily
x/8 = (x+264)/20
3x = 528
x = 176
speed y = 176/8
y = 176/8 *18/5
y = 79.2 km/hr
x/8 = (x+264)/20
3x = 528
x = 176
speed y = 176/8
y = 176/8 *18/5
y = 79.2 km/hr
Vignesh said:
10 years ago
Don't go complex one, we need Speed = Distance/Time.
Total distance = 284.
Time taken to cross is 12 sec (20-8).
Speed = 22 m/s or 79.2 km/hr.
Total distance = 284.
Time taken to cross is 12 sec (20-8).
Speed = 22 m/s or 79.2 km/hr.
(1)
PRIYADARSHI PRATTYULYA KUMAR BHATTA said:
4 years ago
Simply the solution is;
12sec = 264
1sec = 264/12 = 22.
i.e. speed is 22 m / sec.
So we convert it into km/hr.
That is 22*18/5 = 79.2 km/hr.
12sec = 264
1sec = 264/12 = 22.
i.e. speed is 22 m / sec.
So we convert it into km/hr.
That is 22*18/5 = 79.2 km/hr.
(19)
Vishnu said:
3 years ago
D = 264m,
T1 = 8 s,
T2 = 20s,
T = 20-8,
T = 12sec,
S = D/T.
S= 264/12,
S= 22 m/s,
S * 5/18 = 22.
S = 22 * 18/5.
S = 79.2 km/hr.
T1 = 8 s,
T2 = 20s,
T = 20-8,
T = 12sec,
S = D/T.
S= 264/12,
S= 22 m/s,
S * 5/18 = 22.
S = 22 * 18/5.
S = 79.2 km/hr.
(24)
Akhila said:
7 years ago
Please explain this.
After finding the relative speed 20-8=12secs, why we are not taking the total distance as x+264?
After finding the relative speed 20-8=12secs, why we are not taking the total distance as x+264?
Subham kumar said:
1 decade ago
A train passes telegraph post is 40 seconds morning at a rate of 36 km/hr. Then the length of the train is: 8.
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