A 300 m long train crosses a platform in 39 sec while it crosses a signal pole in 18 sec. What is the length of the platform?  Pick:
A) 400m  B) 700m  C) 120m  D) 240m  E) 350m
Explanation:   Speed = 300/18 = 50/3 m/sec.   Let the length of the platform be x meters.   Then, (x + 300)/39 = 50/3   3x + 900 = 1950 =&gt; x = 350 m.   Answer: 350m
<result>E</result>
A 300 m long train crosses a platform in 39 sec while it crosses a signal pole in 18 sec. What is the length of the platform?