CREATE TABLE table_71231 ("Capital" TEXT, "Prefecture" TEXT, "Region" TEXT, "Island" TEXT, "Pop. \\u00b9" FLOAT)

Name the average pop for ch goku and prefecture of okayama
SELECT AVG("Pop. \u00b9") FROM table_71231 WHERE "Region" = 'chūgoku' AND "Prefecture" = 'okayama'
SELECT AVG("Pop. \u00b9") FROM "table_71231" WHERE "Prefecture" = 'okayama' AND "Region" = 'chūgoku'