When there is, within a district, unincorporated territory containing less than one hundred acres and having at least eighty percent of the boundaries of such area contiguous to the district, the board of commissioners may resolve to annex that territory to the district. The resolution shall describe the boundaries of the area to be annexed, state the number of voters residing therein as nearly as may be, and set a date for a public hearing on such resolution for annexation. Notice of the hearing shall be given by publication of the resolution at least once a week for two weeks prior to the date of the hearing, in one or more newspapers of general circulation within the district and one or more newspapers of general circulation within the area to be annexed.