The mean, median and mode of a list, the range, a missing value from the mean, and comparing two sets of data.
What you will learn
- Work out the mean, median, mode and range of a list
- Find a missing value when you know the mean
- Compare two sets of data with an average and the range
- Choose the best average for a set of data
Three averages and one spread
An average is one value that stands for the whole set.
The mean is the total divided by how many values there are. The median is the middle value once the list is in order. The mode is the value that appears most often. The range = largest − smallest measures how spread out the data are.
- Data: 7, 3, 9, 4, 7
- Mean: 7 + 3 + 9 + 4 + 7 = 30, and 30 ÷ 5 = 6
- Median: in order 3, 4, 7, 7, 9, so the middle (3rd) value is 7
- Mode: 7 appears twice, so the mode is 7
- Range: 9 − 3 = 6
With an even number of values the median is halfway between the middle two: for 2, 5, 8, 10 it is (5 + 8) ÷ 2 = 6.5.
The rest of this lesson and its 7 practice questions are locked.
In this lesson
- Three averages and one spread
- Working backwards from the mean
- The slips that cost marks
- Try it: See an extreme value move the mean
7 practice questions, marked as you go; about 20 minutes in all.
Key terms
Mean, Median, Mode, Range
In this unit: Statistics and charts
Averages and range, frequency tables, charts and diagrams, scatter graphs and sampling, and (Higher) cumulative frequency, box plots and histograms.