Question: how do we calculate the time difference from arunachal pradesh to gujarat?
Answer: The western most longitude of india is 68 degree 7 east in gujarat. There is a difference of 4 mins between 2 consecutive longitudes. So difference between 30 longitudes is 30 multiplied by 4 =120 min or 2 hrs. As a result there is a difference of 2 hours between local time of gujarat and arunachal pradesh.