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The mean is the average of a set of numbers. It is the sum of all the items in a set, divided by the total number of items in the set.

A group of numbers can be referred to as a set.

Example: 15, 4, 37, 18, 11.

Mean of two numbers:

When there are only two numbers, the mean is easy to find. It is simply the number that is halfway between the two numbers of the set.


In this example, the set is: 10, 40.

Here, 25 is halfway between 10 and 40, so it is the mean.
Another way to find the mean, or average, is to find the sum of the numbers and divide by 2:

Mean of more than two numbers:
Consider the set: 10, 16, 40.
Here, find the sum of the three numbers and divide by the total numbers in the set, which is three.

Thus, the mean or average, is 22.

Mean in real life:
Example: There is a family with three kids and their ages are: 1, 3, and 5. To find out the mean age of all of the kids in the family, we would, add together all of their ages:
1 + 3 + 5 = 9
and then we would divide that number by the total number of kids.
9 ÷ 3 = 3
The kids in this family have a mean age of 3.