There's no single average class size for LSU. The average class size varies significantly depending on the subject, the level (introductory versus upper-level), the instructor, and even the specific section of a course. Some introductory courses can have hundreds of students, while upper-level seminars might only have a dozen.
LSU doesn't publicly release a single, overall average class size figure. To get a better understanding, you'd need to look at specific course data, which is not readily available in a centralized, publicly accessible format.