CREATE TABLE table_74725 ("Home team" TEXT, "Home team score" TEXT, "Away team" TEXT, "Away team score" TEXT, "Venue" TEXT, "Crowd" FLOAT, "Date" TEXT)

What is the sum of all the crowds that watched North Melbourne at home?
SELECT SUM("Crowd") FROM table_74725 WHERE "Home team" = 'north melbourne'
SELECT SUM("Crowd") FROM "table_74725" WHERE "Home team" = 'north melbourne'