Aptitude - Problems on Trains - Discussion

Hi, Really the explanation given by Dattatray & Rahul was superb. Thanks guys.

Could anyone please tell me how we get to 25/2 by dividing 125/10. I want to know how the division of 125/10 is done to get 25/2 an answer would be appreciated greatly.

Can any one tell me why we have mulipled 25/2 to 18/5..why it should not be multiplied by 5/18 and also how ?

x - 5 = 45 ....as I understand it should be 40 km/hr
x = 50 km/hr. Because x=45.

45-5=40....hence anyone pls clarify.

Now I understand that,.

Distance = Speed*Time.

Time = Distance/Speed.

Speed= Distance/Time.

OK guys, very thanks to your teaching.

Distance = time * speed 125 = 10 * speed
distance/time = speed 125/10 = (25/2)m/s = speed
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Answer should be in km/hr so convert m/s
km = 1000m and hr = 3600s
m = km/1000 and s = hr/3600
m/s = (3600/1000)km/hr
m/s = (18/5)km/hr
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The condition was speed = (25/2)m/s
= (25/2)(18/5)km/hr
= 45 km/hr
The speed was relative to man so we have taken time in consideration of man
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See further in in view answer.
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I could not understand this problem is there any way to understand this more easily.

1km=1000m.
1hour=3600sec.

So to convert from km/hr to m/sec, we need to divide 3600/1000 i.e,.

1km/1hr=3600s/1000m which is equal to 18/5.

If it was asked to convert m/s to km/hr then it would be 1000m/3600s= 5/18

18/5 = 1 km/hr = 1000/3600 m/s

= 10/36 m/s

= 5/18 m/s.

Please explain 18/5.

Answer = 45 km/hr is relative speed of the train.

Now, you calculate (u-v).

The Speed of the train 50 km/hr answer is correct.