The track has a circumference of 400 m. This is the distance traveled per lap.
Because the person made 8 laps, the total distance traveled is
8 * 400 = 3200 m
The time taken for the 8 laps is 14.0 min = 14*60 = 840 s.
The average velocity
= distance/time
= (3200 m)/(840 s)
= 3.8095 m/s
Answer: 3.8 m/s (nearest tenth)