SELECT MAX("Decile") FROM table_68111 WHERE "Authority" = 'state' AND "Name" = 'tarras school'
What is the highest decile of Tarras school, which had a state authority?
CREATE TABLE table_68111 (
    "Name" text,
    "Years" text,
    "Gender" text,
    "Area" text,
    "Authority" text,
    "Decile" real,
    "Roll" real
)