Two trains are running at 40 km/h and 20 km/h respectively in the same direction. Fast train completely passes a man sitting in the slower train in 5 seconds. What is the length of the fast train? Choices:
A) 23 m
B) 23 2⁄9 m
C) 27 m
D) 27 7⁄9 m
E) None of these
Relative speed = (40 – 20) km/h   = (20 × 5⁄18) m/sec = (50⁄9) m/sec   Length of faster train   = (50⁄9 × 5) m = 250⁄9m = 277⁄9 m   Answer 27 7⁄9 m
<result>D</result>
Two trains are running at 40 km/h and 20 km/h respectively in the same direction. Fast train completely passes a man sitting in the slower train in 5 seconds. What is the length of the fast train?