Means, Modes And Medians

MEANS, MODES AND MEDIANS

Means, modes and medians are measures to help describe or summarise a group of numbers.

A) The mean of a group of numbers is the average, calculated by adding the numbers up and dividing by how many numbers there are

B) The mode is the number that occurs the most often. Note that it is OK to have two modes - if there are two numbers in the group that both occur the most often then the group has two modes

C) The median is the middle number when the numbers are placed in ascending order (it is important to do this first!). If there are an even number of numbers then the median is the midpoint between the two middle numbers

Sometimes people get the mode and the median mixed up. You could try to remember each of the measures by putting them in alphabetical order - mean, median, mode - and then noting that average, middle and most, which are descri ptions of each, is also in alphabetical order. There may be other, better, ways to avoid getting them mixed up!

One other measure often used is the range:

D) The range of a group of numbers is the difference (in value) between the highest and lowest numbers in the group

Example

Find the mean, mode, median and range of:

4, 4, 6, 7, 1 and 8

Mean - add the numbers together to get 4+4+6+7+1+8 =30. Now divide by 6 , because there are 6 numbers, to get 5. So the mean is 5

Mode - 4 occurs the most often so the mode is 4

Median - order the numbers in ascending order: 1,4,4,6,7,8 and the median is the midpoint between the two middle numbers 4 and 6. So the median is 5

Range - the range is the difference between the highest and lowest values is 8 and 1 so the range is 7