What is the speed of the train?
I.The train crosses a tree in 13 seconds.
II.The train crosses a platform of length 250 metres in 27 seconds.
III.The train crosses another train running in the same direction in 32 seconds. Answers:  A) I and II only  B) II and III only  C) I and III only  D) Any two of the three  E) None of these
Explanation:   Let the speed of the train be x metres/sec.   Time taken to cross a tree = Length of the train/Speed of the train   Time taken to cross a platform = (Length of the train + Length of the Platform)/Speed of the train   I gives, 13 = l/x = 13x.   II gives 27 = l + 250/x   =&gt; 13x + 250/x = 27   =&gt; x = 125/7 m/sec.   7   Thus I and II give the speed of the train.   I and II onlynswer is (I and II only)
<result>A</result>
What is the speed of the train?
I.The train crosses a tree in 13 seconds.
II.The train crosses a platform of length 250 metres in 27 seconds.
III.The train crosses another train running in the same direction in 32 seconds.