A train 900 m long is running at a speed of 78 km/hr. If it crosses a tunnel in 1 min, then the length of the tunnel is?
Pick one:
A) 288 m
B) 256 m
C) 400 m
D) 278 m
E) 287 m
Speed = 78 * 5/18 = 65/3 m/sec.   Time = 1 min = 60 sec.   Let the length of the train be x meters.   Then, (900 + x)/60   = 65/3   x = 400 m.   Answer:400 m
<result>C</result>
A train 900 m long is running at a speed of 78 km/hr. If it crosses a tunnel in 1 min, then the length of the tunnel is?