Mean
- CBSE · NCERT Class 7 Part 2, Ch 5 Connecting the Dots
The mean of a set of numbers is their total divided by how many numbers there are, often called the average.
The mean shares the total out equally. Its full name is the arithmetic mean. It gives one number that stands for the whole set, so two sets can be compared quickly.
Mean = sum of all the values ÷ number of values.
A small example
A batter scores 12, 45, 30, 8 and 25 runs in five matches. The total is 12 + 45 + 30 + 8 + 25 = 120. There are 5 scores. So the mean is 120 ÷ 5 = 24 runs per match.
Now suppose a sixth match brings 120 runs. The total becomes 240 over 6 matches, and the mean jumps to 40. One very large value, called an outlier, pulls the mean a long way. The median moves far less.
The mean need not be one of the values. Over the first five matches it is 24, a score the batter never made.
Why it matters later
Class 10 Chapter 13 finds the mean of grouped data, where values sit in classes such as 10-20. The idea is the same total-divided-by-count. The assumed mean method is a shortcut that keeps the numbers small.
Sources
Facts last checked against these sources on 30 September 2026.
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