To put it in perspective:
* It's better than average: A 75 on a section suggests a good understanding of the material, however the conversion of this score to the final scaled score depends on the difficulty of the specific practice test you took.
* Significant improvement possible: Top scorers often aim for scores significantly higher than 75 on individual sections. There's considerable potential for improvement through focused study.
* Context matters: The context of the 75 is crucial. Is this a score on a section (e.g., CARS, Biology/Biochemistry), or a scaled score on a full-length practice test? Knowing this is important in evaluating your progress. Also, consider the source of the practice test – some are more accurate predictors than others.
In summary, a 75 is encouraging, demonstrating a solid foundation. However, continuous focused preparation is needed to achieve a highly competitive MCAT score. Analyze your weaknesses, focus on improving those areas, and continue practicing with high-quality materials to maximize your score.