A 300 meter long train crosses a platform in 51 seconds while it crosses a signal pole in 18 seconds. What is the length of the platform?	Pick: A) 550 B) 289 C) 350 D) 882 E) 281

Rationale: "speed = [ 300 / 18 ] m / sec = 50 / 3 m / sec . let the length of the platform be x meters . then , x + 300 / 51 = 50 / 3 3 ( x + 300 ) = 2550 è x = 550 m . answer : a"
Answer: A