Question

How is the standard time of a local determined

Answer 1

Standard time is the synchronization of clocks within a geographical area or region to a single time standard, rather than using solar time or a locally chosen meridian (longitude) to establish a local mean time standard.

Answer 2

a country determines it's standard time by choosing a standard meridian . the degree of it should be divisible by 7°1/2 so that it can be expressed in a multiple of half an hour ahead of Greenwich mean time. ex:82°1/2 is the standard meridian of india