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Discussion Forum



Please study each questions below and all the three statements, numbered I, II and III, and decide whether any information provided in the statement(s) is redundant and can be dispensed with while answering the given question.

1)

What is the length of a running train $A$ crossing another running train $B$ ?

I. These two trains take $18$ seconds to cross to each other.

II. These trains are running in opposite directions.

III. The length of the train $B$ is $180$ metres.


A) I only

B) II only

C) III only

D) All I, II and III are required

E) Even with I, II and III, the answer cannot be obtained.

Answer:

Option E

Explanation:

Let the length of the train $A$ be $x$ metres.

II. These trains are running in opposite directions.

III. Length of the train $B$ is $180$ m.

I. Time taken by $A$ to cross $B$ $=\frac{(180+x)}{Relative\quad speed}$ $\Rightarrow 18$ $=\frac{(180+x)}{Relative\quad speed}$

Thus, even with I, II and III, the answer cannot be obtained.

$\therefore$ Correct answer is (E).