CREATE TABLE "round_13" (
  "home_team" text,
  "home_team_score" text,
  "away_team" text,
  "away_team_score" text,
  "venue" text,
  "crowd" real,
  "date" text
);

Question: What is the average crowd when the home team is north melbourne?
SQL: SELECT AVG("crowd") FROM "round_13" WHERE "home_team"='north melbourne';

Question: What is the crowd total at mcg?
SQL: SELECT COUNT("crowd") FROM "round_13" WHERE "venue"='mcg';