Arithmetic mean of a list.
Arithmetic mean: sum of values divided by count.
Best when data is symmetric and roughly bell-shaped. Skewed distributions are better summarized by median.
A single extreme outlier can pull the mean noticeably in its direction, which is why 'average income' headlines often look higher than what most people actually earn — the median is usually the more representative figure for skewed data like income or home prices.
Numbers: 10, 20, 30, 40. Mean = 100 / 4 = 25.000000.
Mean is affected by outliers; median (middle value) is robust. For income data, median is preferred.
Use the Weighted Grade tool for values with unequal importance.
The mean works well for roughly symmetric data without extreme outliers — test scores or measurement data, for example — where every value should count equally toward the summary.