LIQUOR REVOLVING FUND ‑- FORMULA FOR DETERMINING OFFICIAL POPULATION OF UNINCORPORATED AREA OF COUNTY SUBSEQUENT TO ANNEXATION OF AREA TO A CITY ‑- EXECUTION OF CERTIFICATE The formula for ascertaining the population of the unincorporated area of a county subsequent to annexation of a portion of such area to a city is specifically set out by statute.  The chairman of the board of county commissioners need not join with the mayor in the execution of a certificate as to the population involved in an annexation proceeding.