S = 600/30 = 20 mps
S = 3600/20 = 180 sec = 4 min
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?
A. 4 min
B. 2 min
C. 8 min
D. 3 min
E. 5 min