A 300 m long train crosses a platform in 42 sec while it crosses a signal pole in 18 sec. What is the length of the platform?
Choose the correct answer.
A) 287  B) 350  C) 828  D) 277  E) 400
Speed = 300/18 = 50/3 m/sec.   Let the length of the platform be x meters.   Then, (x + 300)/42 = 50/3   3x + 900 = 2200 =&gt; x = 400 m.   Answer: 400
<result>E</result>
A 300 m long train crosses a platform in 42 sec while it crosses a signal pole in 18 sec. What is the length of the platform?