KVPY SA Exam 2015 Question Paper

Question : 11 of 80

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A man standing on a railway platform noticed that a train took 21 seconds to cross the platform (this means the time elapsed from the moment the engine- enters the platform till the last compartment leaves the platform) which is 88 metres long, and that it took 9 seconds to pass him. Assuming that the train was moving with uniform speed, what is the length o f the train in metres?

Validate

Solution:

Let speed of train is v m/s.
So

v × 21 = 88 + l

⇒

21 v = 88 +l

& also
⇒

v × 9 = l

21 ×l/9 = 88 + l

⇒

l= 66.

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