Mean

In a Nutshell

The mean is the total of all values divided by the number of values: mean=sum of valuesnumber of values\text{mean} = \dfrac{\text{sum of values}}{\text{number of values}}.

The mean is the most commonly used average. It tells you what each value would be if the total were shared out equally.

To find the mean:

  1. Add up all the values to find the total.
  2. Divide the total by how many values there are.

For example, given the data set 4,7,3,10,64, 7, 3, 10, 6:

Mean=4+7+3+10+65=305=6\text{Mean} = \frac{4 + 7 + 3 + 10 + 6}{5} = \frac{30}{5} = 6

The mean does not have to be a whole number, and it does not have to be one of the values in the data set.

Averages and range visualiser A dot plot showing each data value. Annotations mark the mean, median, mode and range on the diagram.

Watch it work

Question: Find the mean of 8,3,12,5,7,98, 3, 12, 5, 7, 9.

Have a go

Q1. Find the mean of 5,10,15,205, 10, 15, 20.

Q2. The mean of 5 numbers is 8. What is their total?

Q3. Four test scores are 72, 85, 68 and 91. Find the mean score.

Q4. Five pupils have a mean height of 1.5 m. A sixth pupil of height 1.62 m joins. What is the new mean?