Table: formula_one_race
Columns: round
name
circuit
date
winning_driver
winning_car

Question: What circuit had an ensign n180 as the winning car in round 5?
SQL: SELECT "circuit" FROM formula_one_race WHERE "winning_car" = 'ensign n180' AND "round" = 5

Question: How many rounds total were there on may 31?
SQL: SELECT COUNT("round") FROM formula_one_race WHERE "date" = 'may 31'

Question: What was the average round for the oulton park circuit?
SQL: SELECT AVG("round") FROM formula_one_race WHERE "circuit" = 'oulton park'