Question

The given question consists of a set of statements. Find out whether the data provided in the statements are sufficient to answer the question and mark the option:

What is the length of the train A?
I. Train A crosses a lamp post in 15 seconds.
II. Train A crosses a platform of length 600 m in 75 seconds.
III. Train A passes through a tunnel 300 m long in 45 seconds.

• A. I and either II or III only
• B. II and III only
• C. II and either I or III only
• D. III and either I or II only
• E. Any two of the three

Answer 1

The correct option is E

Any two of the three

Time taken to cross A =$\frac{Lengthoftrain}{Itsspeed}\Rightarrow 15=\frac{l}{speed}\Rightarrow speed=\frac{l}{15}....\left(i\right)$

Time taken to cross a platform $=\frac{\left(l+600\right)}{speed}$

$\Rightarrow 75=\frac{\left(l+600\right)}{speed}\Rightarrow speed=\frac{\left(l+600\right)}{speed}....\left(ii\right)$

Time taken to pass through a tunnel $=\frac{\left(l+300\right)}{45}$

$\Rightarrow 45=\frac{\left(l+300\right)}{speed}\Rightarrow speed=\frac{\left(l+300\right)}{speed}....\left(iii\right)$

Equating any two out of three will give us ${}^{\prime }{l}^{\prime }$.