In this, if the person starts from A, then after 3.5 rounds, how will the person reaches C? Plz explain briefly.

Dear Student,

One round consist of loop ABCD and half round will be till C as AB+BC=CD+DA.

After each round the person will return to position A$[A\to B\to C\to D\to A]$. After 3 rounds the person will be at position A.
After half round$[A\to B\to C]$, the person will be at point C.

So after 3.5 rounds, the person will be at point C.

Regards,