Statistics and Probability
Data handling
Find the mean, median, mode and range of a set of data, and read information off a bar chart.
A long list of numbers is hard to think about, so we squash it into one number that stands for the whole set. There are three ways of doing it and they answer slightly different questions, which is why all three have names.
The three averages, and the range
The mean is the total shared out equally: add everything up and divide by how many there are. The median is the middle value once the numbers are in order. The mode is the value that appears most often. The range is not an average at all — it is the gap between the largest and the smallest, and it tells you how spread out the data is.
Worked example
Find the median of 9, 4, 7, 2, 6 and 10.
Put them in order: 2, 4, 6, 7, 9, 10.
The median is about position, so the order has to be right before anything else can happen.
Try it together
Now let us describe one set of data three different ways. A team scored 2, 5, 3, 5 and 0 goals in five matches.
Same five numbers, three averages. Watching them come out differently is the point of the exercise.
1.Add them all up. What is 2 + 5 + 3 + 5 + 0?
Have a go
Have a go on your own: find the mean of 6, 9 and 12.
Hint: Add the three, then divide by three.
Ready to practice?
Eight questions on what you have just read. Nothing is timed, and you can play as many times as you like.