Aptitude - Problems on Trains - Discussion
Discussion Forum : Problems on Trains - General Questions (Q.No. 2)
2.
A train 125 m long passes a man, running at 5 km/hr in the same direction in which the train is going, in 10 seconds. The speed of the train is:
Answer: Option
Explanation:
| Speed of the train relative to man = |  |
125 |  m/sec |
| 10 |
| = | |
25 | m/sec. |
| 2 |
| = | |
25 | x | 18 | km/hr |
| 2 | 5 |
= 45 km/hr.
Let the speed of the train be x km/hr. Then, relative speed = (x - 5) km/hr.
x - 5 = 45 
x = 50 km/hr.
Discussion:
493 comments Page 16 of 50.
Sivalaxman said:
9 years ago
They are two formulas for this,
1. X mts/sec = X*18/5 km/hr,
2. X km/hr = X*5/18mts/sec,
When you see the question the options are given in km/hr then we 1. Formula for this solution.
1. X mts/sec = X*18/5 km/hr,
2. X km/hr = X*5/18mts/sec,
When you see the question the options are given in km/hr then we 1. Formula for this solution.
Ravi said:
1 decade ago
It is given that
Speed of man=5km/hr
Distance travelled by man in 10s=125/9m
Distance travelled by train in 10s= {125+(125/9)}m
Hence
Speed of train = [{125+(125/9)/10]*3600 = 50 km/hr
Speed of man=5km/hr
Distance travelled by man in 10s=125/9m
Distance travelled by train in 10s= {125+(125/9)}m
Hence
Speed of train = [{125+(125/9)/10]*3600 = 50 km/hr
Saranya said:
2 decades ago
hai raghu, in the question man's speed is given in km/hr so we gonna convert train's speed to km/hr which is actually in m/s
1 m/s = 3600 km/1000 hr
125/10 m/s= (125/10)*(3600/1000)
1 m/s = 3600 km/1000 hr
125/10 m/s= (125/10)*(3600/1000)
Prosenjit said:
8 years ago
Let the speed of the train x in one second.
So their combined speed=x-{5000/(60*60)}=x-1.39 in one second,
so, 125/x-1.39=10,
x=13.89 (in one second),
So 50000m=50 km in hour.
So their combined speed=x-{5000/(60*60)}=x-1.39 in one second,
so, 125/x-1.39=10,
x=13.89 (in one second),
So 50000m=50 km in hour.
Shiwam said:
1 decade ago
@vandna
It is option checking question so option must be given.
Since it has 3 variables plateform length,train length & train speed.
it might be done by option checking.
It is option checking question so option must be given.
Since it has 3 variables plateform length,train length & train speed.
it might be done by option checking.
Shailesh said:
1 decade ago
Speed of train=(length of train/time) is a formula
hence,
125/10 m/sec
now (125/10)*(18/5)=45.. multiply by 18/5 to become km/h
now 45 is relative speed
sr=s1-s2
45=s1-5
s1=50
hence,
125/10 m/sec
now (125/10)*(18/5)=45.. multiply by 18/5 to become km/h
now 45 is relative speed
sr=s1-s2
45=s1-5
s1=50
Mubarak said:
10 years ago
Thank you guys for your best explanations really easily understandable, for the non maths learners. You people are doing good, good things never stop. Please keep on posting.
Priyan singh said:
1 decade ago
How can be its 50 ?
It's 45 km/hr.
If we put answer 45 km as speed of train.
Time = 125/45*5/18 = 10 m/s.
But if we 50 we can't get its time. 10 m/s.
Explain someone ?
It's 45 km/hr.
If we put answer 45 km as speed of train.
Time = 125/45*5/18 = 10 m/s.
But if we 50 we can't get its time. 10 m/s.
Explain someone ?
Kaushik Rathod said:
2 decades ago
Answer in Another way :-
Speed = 5*18/5 = 18 km/hr
Time = 10 sec.
X + 125 / 10 = 18
X + 125 = 180
X = 180-125
X=55
Now, Speed = X-5
So , Speed = 55 - 5
Speed = 50 km/hr
Speed = 5*18/5 = 18 km/hr
Time = 10 sec.
X + 125 / 10 = 18
X + 125 = 180
X = 180-125
X=55
Now, Speed = X-5
So , Speed = 55 - 5
Speed = 50 km/hr
Adesh Katiya said:
2 years ago
l = 125m,
u = 5km/hr,
v = ?
t = 10s.
u - v = 125/10 m/s,
u - v = 25/2 m/s,
u - v = 5*9 km/hr,
u - v = 45km/hr,
5km/hr - v = 45km/hr.
v = 50 km/hr.
Hence, option (B).
u = 5km/hr,
v = ?
t = 10s.
u - v = 125/10 m/s,
u - v = 25/2 m/s,
u - v = 5*9 km/hr,
u - v = 45km/hr,
5km/hr - v = 45km/hr.
v = 50 km/hr.
Hence, option (B).
(47)
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