Mean, Range, Median and Mode

An average is a single value that represents a set of numbers.

 

Mean

To calculate the mean:

  • add up all the values
  • divide by the number of values.

Example: Work out the mean of the following numbers 2, 4, 2, 3, 7.

The mean: Add them all up and divide by the total number of items.

  • Add them up: 2 + 4 + 2 + 3 + 7 = 18
  • Number of items = 5
  • Mean = 18/5 = 3.6

Range

The range of a set of data tells you how widely the numbers are spread.

Range = the biggest value – the smallest value.

Example: Work out the range of the following numbers 2, 4, 2, 3, 7.

Range: largest – smallest 7 – 2 = 5

Median

The median of a set of data is the middle value when the data values are placed in order.

To work out the median:

  • Put the numbers in ascending (increasing) order.
  • Cross out the extremes until you are left with one number.
  • If you are left with two numbers, add them up and divide by 2.

Example: Work out the median of the following numbers 2, 4, 2, 3, 7.

Median: Put the numbers in ascending order from smallest to the largest.

2 2 3 4 7

Then cross the ends off until you are left with one number. If you are left with two, work out the mean of these two numbers.

2 2 3 4 7

Mode

The mode of a set of data is the value that occurs most often.

Example: Work out the mode of the following numbers 2, 4, 2, 3, 7.

Mode: Most common number.

2, 2, 3, 4, 7 ; 2 is the most common.