How do you compute the arithmetic mean of a finite set of numbers?

Conditions

• The data set contains a finite number of values.
• All values are numerical.

Reasoning, step by step

1. List all the numbers in the dataset.
2. Calculate the sum of all the numbers.
3. Count the total number of values in the dataset.
4. Divide the sum by the count to obtain the mean.

Example

For the scores 15, 20, 25, 20, 20, the sum is $15+20+25+20+20 = 100$. Dividing by the count of 5 gives $100/5 = 20$.

Common misconceptions

• Forgetting to divide the sum by the number of observations.
• Including non-numerical data in the sum.

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