Final answer:
To compare students' GPAs to their respective school averages, z-scores are used. John's less negative z-score (-.21) compared to Ali's (-.30) suggests his GPA is closer to his school's mean. However, Anita, with a z-score indicating she is 0.70 standard deviations above her school average, has the best comparative GPA.
Step-by-step explanation:
To determine which student has the best GPA compared to their school, you need to look at their GPA in the context of their school's grading distribution. This is often represented by a z-score, which indicates how far and in what direction an individual's score deviates from the mean, measured in standard deviations. John has a higher z-score (less negative) than Ali, meaning his GPA is closer to the school's mean. If the z-score is less negative, it indicates that the student's GPA is higher in comparison to the school's average GPA.
Ricardo's GPA is the same as the average GPA at his school, which means his z-score would be 0. Anita, with a GPA of 0.70 standard deviations above her school average, would have a positive z-score, indicating she is above the school average. Comparatively, Anita likely has the best GPA since her score is above the school average, while Ricardo's is just average, and John's is still below the mean, although not as far below as Ali's.