Averages and range · Year 9
In Year 9 you learn: the mean from a frequency table.
An average is one number that represents a whole set of data. The mean shares the total out equally. The median is the middle value. The mode is the most common value. The range measures how spread out the data are.
Key facts
- Median: put the values in order. It is the middle one, or halfway between the middle two.
- Mode: the value that occurs most often. There can be more than one mode, or none.
- Range = largest value − smallest value.
- From a frequency table: mean = (Σfx)/(Σf).
- An outlier drags the mean but hardly moves the median.
Worked examples
Example 1
Find the mean, median, mode and range of 4, 8, 3, 8, 7.
Answer: Mean 6, median 7, mode 8, range 5
Example 2
The table shows the goals scored in 20 football matches. Find the mean and the median.
Answer: Mean 1.5, median 1