A 300 meter long train crosses a platform in 39 seconds while it crosses a signal pole in 18 seconds. What is the length of the platform. Select the correct option.
A) 310 meter  B) 335 meter  C) 345 meter  D) 350 meter  E) none of these

Rationale: "explanation : speed = distance / time = 300 / 18 = 50 / 3 m / sec let the length of the platform be x meters then distance = speed ∗ time x + 300 = 50 / 3 ∗ 39 = > 3 ( x + 300 ) = 1950 = > x = 350 meters option d"
Answer: D