The man takes 40 sec to cover ( 4 * 10 ) 40 metres. This shows he covers one metre in one sec.
In 2 min 20 sec (140 sec) , he will cover a distance of 140 metres.
Thus he completes 14040 = 3.5 rounds in 2 min 20 sec.
Hence it is noticed that he will be at the opposite side from where he started.
Now considering two simple cases.
If the man started at a corner of the square street:
In this case, the man would be diagonally opposite to the place from where he started
Displacement = diagonal of square with side 10 metre.
The man started from the middle of the road.
After the end time, he is in the opposite side of the road.
Hence, the displacement is 10 metre.
-Answered by Master Purushottam On 24 August 2019:12:11:55 AM