Distance covered in one complete round ie., 40 sec.
= circumference of circle of diameter 200 m
= π 200 meters.
Distance covered in 2 mins 20 sec or 140 sec: = 200 π * 140/40 = 700 π meters
In 140 seconds, the athlete makes 3 complete rounds and runs for 20 secs after that.
in 40 secs, he runs a complete circle (covers 360°). So in 20 secs, athlete runs half-circle and covers 180°.
So at the end of 140 seconds, athlete is at the diametrically opposite end on the circular track.
The displacement = vector joining the initial position to the final position.
It magnitude = diameter = 200 meters.