To compete at state level

No, you cannot compete if you don't have 5 credits at 1 sitting

Students must also satisfy a number of other criteria, including:

(a) have a minimum of six Credits, including English Language, at one sitting (or five Credits at one sitting and a sixth at a later sitting. Again English Language must be one of the subjects);

(b) not have more than 10 days of absence from school in the Lower Sixth or Upper Sixth without due cause;

(c) not have reached the age of 20 before the 1st July in the year that the student takes the HSC exams.