When POST electronically scans your test answers, statistical calculations are performed to convert your raw score (the number of items you answered correctly) into a “T-score.” A T-score is a standardized score that places your performance on the test into a distribution (bell-shaped curve) with a midpoint (average) of 50 and a standard deviation of 10. If your score falls around 50, your performance is considered “average” when compared to other applicants who have taken the test. If you score 40 or below, your performance is considered “below average” when compared to other applicants who have taken the test. If you score 60 or above, your performance is considered “above average” when compared to other applicants who have taken the test. Research shows that the likelihood of successful academy completion increases for every point above 42 you score.
Right from the POST site:
http://www.post.ca.gov/FAQ/Program_Specific/Entry_Level/Applicant.asp