A train crosses a bridge of length 150 m in 7.5 seconds and a lamp post on the bridge in 2.5 seconds. What is the length of the train in metres?	Options:  A) 37.5 m  B) 75 m  C) 25 m  D) 80 m  E) 30 m
Let Length of Train = L   Case-1: Distance = 150+L (While crossing the bridge)   Time = 7.5 Seconds   i.e. Speed = Distance / Time = (150+L)/7.5   Case-2: Distance = L (While passing the lamp post)   Time = 2.5 Seconds   i.e. Speed = Distance / Time = (L)/2.5   But Since speed has to be same in both cases so   (150+L)/7.50 = (L)/2.5   i.e. 3L = L + 150   i.e. 2L = 150   i.e. L = 75   Answer: option 75 m
<result>B</result>
A train crosses a bridge of length 150 m in 7.5 seconds and a lamp post on the bridge in 2.5 seconds. What is the length of the train in metres?