Problems on Trains - Arithmetic Aptitude Questions and Answers

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What is the length of a running train?
I.The train crosses a man in 9 seconds.

II.The train crosses a 240 metre long platform in 24 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 by train to cross a man =		$\frac { Length of train } { Speed of train}$ Speed =		$\frac { l } { 9 }$ ....(i)

Time taken by train
to cross a platform =

$\frac {( Length of train + Length of platform) } { Speed of train}$

Speed =

$\frac { l + 240 } { 24 }$ ....(ii)

From (i) and (ii), we get		$\frac { l } { 9 }$ =		$\frac { l+240 } { 24 }$