A train 700 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?  Select:
A) 298 m
B) 468 m
C) 600 m
D) 667 m
E) 781 m
Speed = 78 * 5/18 = 65/3 m/sec.   Time = 1 min = 60 sec.   Let the length of the train be x meters.   Then, (700 + x)/60 = 65/3   x = 600 m.   Answer: 600 m
<result>C</result>
A train 700 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?