What is the sum of the areas for populations of 542?
CREATE TABLE "carleton_county_new_brunswick" (
  "official_name" text,
  "status" text,
  "area_km_2" real,
  "population" real,
  "census_ranking" text
);
SELECT SUM("area_km_2") FROM "carleton_county_new_brunswick" WHERE "population"=542;