Question

Train 'A' running at a certain speed crosses another train 'B' running at a certain speed in the opposite direction in 12 seconds. What is the length of train 'B'?
I. The length of both the trains together is 450 metres.
II. Train 'A' is slower than train 'B'.

• A. Data in the statement I alone are sufficient to answer the question, while the data in statement II alone are not sufficient to answer the question.
• B. Data in statement II alone are sufficient to answer the question, while the data in statement I alone are not sufficient to answer the question.
• C. Data either in statement I alone or in statement II alone are sufficient to answer the question.
  
• D. Data given in both the statements I and II together are not sufficient to answer the question.
  
• E. Data in both the statements I and II together are necessary to answer the question.

Answer 1

The correct option is D Data given in both the statements I and II together are not sufficient to answer the question.


Let $S_1$ and $S_2$ be the speed of train A and B respectively Time taken by both the trains in crossing each other.
$\frac{450}{S_1+S_2}=12,S_1+S_2=37.5$
$S_1$ and $S_2$ can have so many values. Both statements I and II are not sufficient to find the length of train B.