Question

Why do we need standard time

Answer 1

We need a standard meridian for India because of the vast longitudinal extent of the mainland. 

Answer 2

We need standard meridian time because of the vast longitudinal extent of the mainland . Thus there is a lag time from Gujarat to Arunachal Pradesh. Hence time along the standard meridian of India passing through Mirapur is taken as Standard time for the whole country.

Hope it helps you!!!