CREATE TABLE table_204_547 (id DECIMAL, "rank" DECIMAL, "lane" DECIMAL, "name" TEXT, "nationality" TEXT, "time" DECIMAL, "notes" TEXT)

what was the time of the last finisher ?
SELECT "time" FROM table_204_547 ORDER BY "rank" DESC LIMIT 1
SELECT "time" FROM "table_204_547" ORDER BY "rank" DESC NULLS LAST LIMIT 1