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