A 300 metre long train crosses a platform in 39 seconds while it crosses a post in 18 seconds. What is the length of the platform? Choose the correct choice from the following
A) 300m	B) 200m	C) 250m	D) 350m	E) 400m
Length of the train = distance covered in crossing the post = speed × time = speed × 18   Speed of the train = 300/18 m/s = 50/3 m/s   Time taken to cross the platform = 39 s   (300+x)/(50/3) = 39 s where x is the length of the platform   300+x = (39 × 50) / 3 = 650 meter   x = 650-300= 
<gadget id="calculator">650-300</gadget>
<output>350</output>
350 meter   Answer is 350m.
<result>D</result>
A 300 metre long train crosses a platform in 39 seconds while it crosses a post in 18 seconds. What is the length of the platform?