Discussion :: Problems on Trains

What is the speed of the train whose length is 210 metres?
I.
The train crosses another train (Howrah Express/12869) of 300 metres length running in opposite direction in 10 seconds.
II.
The train crosses another train (Howrah Express/12869) running in the same direction at the speed of 60 km/hr in 30 seconds.
A.
I alone sufficient while II alone not sufficient to answer 

B.


C.


D.


E.

Answer : Option E
Explanation :
Time taken to cross the train, running in opposite directions 
=\({ (l1 + l2) \over (u + v)}sec\)  .  
\(10= {(210 + 300) \over (u + v)}\)  
u + v = 51.
Time taken to cross the train, running in same direction  \(= {(l1 + l2) \over (u  v)} sec\)sec.  
30 = \({(210 + 300) \over (u  60 \times )(5/18)}\)  
u =  \( (17+\frac{50}{3})m/sec\)  
Thus, u and v can be obtained.
Correct answer is (E).
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