If there was no standard meridian for India,the time would differ from state to state.
So this creates confusion among people.For example if a person starts from Gujarat at 10:00AM and he needs to reach Andra Pradesh by 5:00PM but due to time difference he may reach Andra Pradesh by 8:00PM or something.So to avoid this we have a standard meridian as 82 1/2°E.

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8 4 8
We should use standered meredian only in india or the peoples will not understand the timings properly
3 3 3
India has o large longitudinal expanse with time differing from 4 to 5 minutes for distance between each meredien. As a result we will have lots of confusion on what the time is. Therefore we refer to a single meridien.