Mean

The mean is the average of a set of numbers.

It is calculated by dividing the sum of all the items in a set by the total number of items in the set.

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

Example

a.)15, 4, 37, 18, 11

b.) 6, 6, 7, 9, 11, 11, 15, 20

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.

Example

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.

In this example, we would add 10 and 40 and divide the obtained sum by 2 which gives us a mean of 25 for our set.

Example

Consider the set: {10, 16, 40}

Here, we will find the sum of the three numbers and divide by 3.

The mean, or average, is 22.

Example 1

• There is a family with three kids and their ages are: 1, 3, and 5. Find out the mean age of all of the kids in the family.

To find the mean, we will follow the following steps:

Add together all of their ages.

i.e. 1 + 3 + 5 = 9

and then you would divide that number by the total number of kids.

So, 9 ÷ 3 = 3

The kids in this family have a mean age of 3.

Example 2

• A store is selling 2 puppies, and needs to weigh them before they go home with their new owners. The first puppy weighs 3 pounds. The second puppy weighs 7 pounds. What is the mean weight between the two puppies?

Add up their weights.

3 + 7 = 10

Divide the total weight by the total number of puppies.

10 ÷ 2 = 5

The puppies in this store have a mean weight of 5 pounds.