Discussion :: Problems on Trains

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
A.


B.
II alone sufficient while I alone not sufficient to answer 

C.


D.


E.

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  \(\frac { l } { 9 } \)=  \(\frac { l+240 } { 24 }\)  
Thus, l can be obtained. So both I and II are necessary to get the answer.
The correct answer is (E).
Be The First To Comment