A 600 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? Choose one:	A) 800	B) 700	C) 360	D) 370	E) 380

Rationale: "speed = 600 / 18 = 100 / 3 m / sec . let the length of the platform be x meters . then , ( x + 300 ) / 39 = 100 / 3 = > x = 1300 m . l = 1300 - 600 = 700 m answer : option b"
Answer: B