Average (Mean)

The average, or mean, gives one representative value for a group of numbers by sharing the total equally across all the items. It works because if you add the same amount to each value, you can still get the same total; dividing the total by the number of values tells you what each value would be if they were evenly spread out. This makes the mean useful for summarizing a set of data with a single number.

Use this when you want to find a typical value from a list of measurements or scores, such as test marks, temperatures, or times. It is also helpful when comparing two groups that may have different individual values but a similar overall level.

• Forgetting to divide by the number of values after adding
• Counting values twice or leaving one out
• Using the median or mode instead of the mean