(a)office of Chairperson in the Municipalities shall be reserved for the Scheduled Castes and the Scheduled Tribes and the number of offices so reserved for the Scheduled Castes and the Scheduled Tribes shall bear, as nearly as may be, the same proportion to the total number of such offices as the population of the Scheduled Castes and the Scheduled Tribes respectively [in the Municipal areas of the State bears to the total population of such Municipal areas;]