CREATE TABLE table_64104 ("School" TEXT, "Location" TEXT, "Mascot" TEXT, "Size" FLOAT, "IHSAA Class" TEXT, "# / County" TEXT, "Year Joined" FLOAT, "Previous Conference" TEXT)

What's the size of Centerville in 89 Wayne county with an IHSAA class of AA in the year before 1974?
SELECT "Size" FROM table_64104 WHERE "Year Joined" < '1974' AND "IHSAA Class" = 'aa' AND "# / County" = '89 wayne' AND "School" = 'centerville'
SELECT "Size" FROM "table_64104" WHERE "# / County" = '89 wayne' AND "IHSAA Class" = 'aa' AND "School" = 'centerville' AND "Year Joined" < '1974'