Question

To calculate the difference between the local times of any tow places on the earth?

Answer 1

Answer:

There is a difference in the time  as you travel from east to west or west to  east. When you are travelling West to East  you gain time of 4 minutes as you cross every  longitude. But if you are travelling from East  to West you lose 4 minutes as you cross  every longitude. These are referred as EGA  and WLS (EGA - East Gain Add, WLS - West  Lost Subtract).

So if the time at 0° longitude is 12:00 p.m. then, the time at 15°E longitude will be:

15(longitude)×4(minutes)

15×4=60 minutes

So, the time is 60 minutes ahead i.e., 1:00 p.m.

Time at longitudes towards east would be 4 minutes ahead each longitude and longitude towards west would be 4 minutes behind.

So, time at  82°30' E would be 5+30hrs past Greenwich time.

that is if the current time at 0° longitude is 4:00 p.m. then the time at 82°30' E would be 9: 30 p.m.