Final answer:
The percentile rank is the best statistic to determine if a score of 30 is high compared to the rest of the group.
Step-by-step explanation:
The statistic that would best help answer the question, "Is a score of 30 a high score given how the rest of the group performed?", is the percentile rank.
The percentile rank tells us the percentage of scores that are below a given score. By finding the percentile rank of 30, we can determine if it is a high score compared to the rest of the group.
To find the percentile rank of 30, we need to determine the percentage of scores that are below 30. Depending on the available data, we can calculate this by finding the cumulative percentage or by finding the cumulative frequency and using it to determine the rank.
For example, if the 70th percentile corresponds to a score of 25, then a score of 30 would be considered high because it is above the 70th percentile.