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 then mark the appropriate option.

What is the speed of the bullet train?

I. The train crosses a lamp post in 26 seconds.

II. The train crosses a platform of length 500 metres in 54 seconds.

III. The train crosses another train running in the same direction in 64 seconds.

• A. I and II only
• B. II and III only
• C. I and III only
• D. None of these

Answer 1

The correct option is A

I and II only

Let the speed of the train be `x' m/sec.

Time taken to cross a lamp post $=\frac{Lengthofthetrain}{Speedofthetrain}$

Time taken to cross a platform = $=\frac{\left(Lengthoftrain+Lengthofplatform\right)}{Speedofthetrain}....\left(ii\right)$

$Igives,26=\frac{l}{x}\Rightarrow l=26xIIgives,54=\frac{l+500}{x}\Rightarrow \frac{26x+500}{x}=54\Rightarrow x=\frac{125}{7}m/sec.$

Thus I and II give the speed of the train.