1. Averages….. In table form

2. We will start with discrete data i.e. the data can only take certain values e.g. shoe size

3. Number of children in a car No. of children in carFrequency (or No. of cars) 03 19 25 32 41

4. The mode means ……. most common

5. The mode is ……. 1 child per car

6. The range is the Highest number of children – smallest number (per car)

7. So the range = 4 – 0 = 4

8. It is NOT ….. 9 – 1 = 8

9. median Put in size order (Already done in our table) Find the middle value

10. We have 20 pieces of data To find the position of the data value we need…. Add 1 onto the number of data values 21 Half this 10½ We need to look halfway between the 10 th and 11 th pieces of data 1 and 1 So the median is ……….

11. 1

12. Now for the trickiest bit…. The mean

13. We need to find the total number of children in the cars And then divide by the total number of cars

14. Add a column to your table No. of children Frequency (No. of cars) Group total 030 x 3 = 0 191 x 9 = 9 252 x 5 = 10 323 x 2 = 6 414 x 1 = 4 TOTAL2029

15. Mean number of children per car …… Total No. of children ÷ total frequency

16. Mean = 29 ÷ 20 = …….. 1.45 children per car

17. One for you then…… No. of rings per studentFrequency 073 115 27 34 41

18. Mode (most common) = … 0 rings

19. Range = ……. 4 rings – 0 rings = 4

20. Median …… 100 pieces of data Do the ‘add one and half business’ which leaves us looking for the 50½ value (in between the 50 th and 51 st values) 50 th value is ‘0’ and 51 st value is also ‘0’ So median is 0

21. Mean …… New column on table

22. Like this …… No. of ringsFrequencyGroup Total 0730 x 73 = 0 1151 x 15 = 15 272 x 7 = 14 343 x 4 = 12 414 x 1 = 4 TOTAL100 45

23. Mean = 45 ÷ 100 = …… 0.45

24. Here’s another one …… No. of fingersFrequency 81 92 1046 110 121

25. Mode = ……. 10

26. Range = …… 12 – 8 = 4

27. Median 50 data values so do the ‘add 1 and half’ thing – we want the 25 th and 26 th values Median is 10

28. Mean No. of fingersFrequencyGroup total 818 x 1 = 8 929 x 2 = 18 104610 x 46 = 460 11011 x 0 = 0 12112 x 1 = 12 TOTAL 50 498

29. Mean = 498 ÷ 50 = 9.96