A train runs across a post in 15 seconds and across a platform of length 100m in 25 seconds. Determine the length of this train:  Pick
A) 137 B) 150 C) 287 D) 167 E) 172
Explanation:   Let us assume for this question that the length of train is x metres and it is assumed to be running at the speed of y m/sec.   A pole is assumed as a point object.   =&gt;Time taken by the train to pass the pole= x/y   =&gt;15=x/y   =&gt;y=x/15   Now, the train passes the platform which is 100 m in length in 25 seconds.   =&gt;x+100/y=25   =&gt;x+100/25=y   Equating speed generated from both cases:   x+100/25=x/15   Therefore x = 150 metres.   ANSWER: 150
<result>B</result>
A train runs across a post in 15 seconds and across a platform of length 100m in 25 seconds. Determine the length of this train: