Given the following reasoning and answer, what was the question? S = 600/30 = 20 mps
S = 3600/20 = 180 sec = 4 min
 The answer: (D)

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
The question A 600 meter long train crosses a signal post in 30 seconds. How long will it take to cross a 3 kilometer long bridge, at the same speed?
Options:
(A) 4 min
(B) 2 min
(C) 8 min
(D) 3 min
(E) 5 min