Question

explain how the standard time of a country is calculated why do we have a standard time​

Answer 1

Answer:

our standard time is set by subtraction of the latitudinal and longitudinal extensions which is 30degree Approx

Also the standard meridian was set in the state of Uttar Pradesh (mirzapur) .

Answer 2

The time at any place is measured in reference to time at Prime Meridian(0 degree). Our earth rotates 360 degree(1 rotation) in 24 hours(1440 minutes). So, to rotate 1 degree, it takes 4 minutes. Standard time of a place is calculated in reference to the standard time at 0 degree latitude(Greenwich Mean Time, GMT).

Hope it helps