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.
