Problems on Trains - Arithmetic Aptitude Questions and Answers

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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.

I alone sufficient while II alone not sufficient to answer

II alone sufficient while I alone not sufficient to answer

Either I or II alone sufficient to answer

Both I and II are not sufficient to answer

Both I and II are necessary to answer

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 =				\( (17+\frac{50}{3})m/sec\)