Question: What is Average ?


An average is a single number which is used to represent a collection of numerical data. An average is a single value that is meant to typify a list of values. If all the numbers in the list are the same, then this number should be used. If the numbers are not all the same, an easy way to get a representative value from a list is to randomly pick any number from the list. However, the word average is usually reserved for more sophisticated methods that are generally found to be more useful.

There are various types of average. Three averages which are commonly used are the mean (or arithmetic mean), the median, and the mode. These are defined and illustrated using the following example.

In a skittles match Tina scored 6, 5, 8, 12, 3, 5, 7, 7, 5 in her nine goes.

The mean is obtained by dividing the sum of all the data by the number of data.
(6 + 5 + 8 + 12 + 3 + 5 + 7 + 7 + 5) ÷ 9

This gives the mean as 6.44 to 2 decimal places. Note that this number is not obtainable as a score, but it represents Tina’s skill at skittles on the day

The median is the middle score if the scores are put in order of size 3 5 5 5 6 7 7 8 12

The middle score in this set of data is the 5th number along, namely 6, so 6 is the median score. If there were an even number of scores, the median would be taken as the mean of the middle two scores.

The mode is the number which occurs most often. In this example 5 is the most frequently occurring score, so 5 is the mode.