7th Grade · Statistics & Probability
Center
7.SP.B.3
Definition
A representative value near the middle of a data set. Mean = sum ÷ count. Median = middle value when ordered. Use median when outliers are present.
Examples
- {2,4,5,6,6,7,8,9,23}: median = 6, mean ≈ 7.8 (pulled toward the outlier 23).
- Without outliers, mean or median both work well.
Key rule
Outliers affect the mean but not the median.
Memory hook
Mean balances the data; median splits it in half.