Problems on Trains - Arithmetic Aptitude Questions and Answers

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What is the speed of the train?

I. The train crosses a signal pole in 18 seconds.

II. The train crosses a platform of equal length in 36 seconds.

III. Length of the train is 330 metres

I and II only

II and III only

I and III only

III and either I or II only

Any two of the three

Answer : Option D

Explanation :

Let the speed of the train be x metres/sec.

Time taken to cross a signal pole = \(\frac { Length of the train} { Speed of the train } \)

Time taken to cross a platform = \(\frac { (Length of the train + Length of the Platform) } { Speed of the train } \)

Length of train = 330 m.

I and III give, 18 = \(\frac { 330 } { X }\)		x = \(\frac { 330 } { 18 } \)		m/sec =		\(\frac { 55} { 3 } \)m/sec.

II and III give, 36 =		\(\frac { 2 \times 330 } { X } \) x =		\( \frac { 660 } { 36 } \)m/sec =		\(\frac { 55 } { 3 } \)m/sec.