1. Created by Mr Lafferty Maths Dept
Statistics
Interpreting / Drawing Graphs
Averages and Interpreting Data
Mean from Mid-Interval Frequency Table
Scatter Diagrams
Frequency Polygons
20-Nov-18
Created by Mr Lafferty Maths Dept

2. Created by Mr Lafferty Maths Dept
Starter Questions
20-Nov-18
Created by Mr Lafferty Maths Dept

3. Created by Mr Lafferty Maths Dept
Statistics
Interpreting Graphical Data
Learning Intention
Success Criteria
To revise the various types of graph used to display statistical data.
To be able to recognise the various types of graph that can be used to display statistical data.
Interpret graphs.
20-Nov-18
Created by Mr Lafferty Maths Dept

4. Statistics Bar Chart www.mathsrevision.com
Write down a question you could answer using this graph
20-Nov-18
Created by Mr Lafferty Maths Dept

5. Statistics Comparing Line graphs
Write down a question you could answer using this graph
Statistics Comparing Line graphs
20-Nov-18
Created by Mr Lafferty Maths Dept

6. Statistics Bar Chart www.mathsrevision.com
Write down a question you could answer using this graph
20-Nov-18
Created by Mr Lafferty Maths Dept

7. Statistics Pie Chart www.mathsrevision.com
Write down a question you could answer using this graph
20-Nov-18
Created by Mr Lafferty Maths Dept

8. Created by Mr Lafferty Maths Dept
Statistics
Interpreting Graphical Data
S4 General
Now try Ex 1A
Ch5 (page 57)
20-Nov-18
Created by Mr Lafferty Maths Dept

9. Created by Mr Lafferty Maths Dept
Starter Questions xo
42o
20-Nov-18
Created by Mr Lafferty Maths Dept

10. Created by Mr Lafferty Maths Dept
Statistics
Averages
Learning Intention
Success Criteria
To explain the terms mean, range, median and mode.
Understand the terms mean, range, median and mode.
To be able to calculate mean, range, mode and median.
20-Nov-18
Created by Mr Lafferty Maths Dept

11. Created by Mr Lafferty Maths Dept
Statistics
Finding the mode
S4 General
The mode or modal value in a set of data is the data value that appears the most often.
For example, the number of goals scored by the local football team in the last ten games is: 2, 1, 0, 3, 1. 2, 1, 0, 3, 1.
What is the modal score? 2.
Is it possible to have more than one modal value?
Yes
Is it possible to have no modal value?
Yes
20-Nov-18
Created by Mr Lafferty Maths Dept

12. Created by Mr Lafferty Maths Dept
Statistics
The mean
S4 General
The mean is the most commonly used average.
To calculate the mean of a set of values we add together the values and divide by the total number of values.
Mean =
Sum of values
Number of values
For example, the mean of 3, 6, 7, 9 and 9 is
20-Nov-18
Created by Mr Lafferty Maths Dept

13. Created by Mr Lafferty Maths Dept
Statistics
Finding the median
S4 General
The median is the middle value of a set of numbers arranged in order. For example,
Find the median of
10, 7, 9,
12, 8, 6,
Write the values in order: 6, 7, 7, 8, 9,
10,
12.
The median is the middle value.
20-Nov-18
Created by Mr Lafferty Maths Dept

14. Created by Mr Lafferty Maths Dept
Statistics
Finding the median
S4 General
When there is an even number of values, there will be two values in the middle.
For example,
Find the median of 56, 42, 47, 51, 65 and 43.
The values in order are:
42,
43,
47,
51,
56,
65.
There are two middle values, 47 and 51. 2 = 98 2
= 49
20-Nov-18
Created by Mr Lafferty Maths Dept

15. Created by Mr Lafferty Maths Dept
Statistics
Finding the range
S4 General
The range of a set of data is a measure of how the data is spread across the distribution.
To find the range we subtract the lowest value in the set from the highest value.
Range = highest value – lowest value
When the range is small; the values are similar in size.
When the range is large; the values vary widely in size.
20-Nov-18
Created by Mr Lafferty Maths Dept

16. Created by Mr Lafferty Maths Dept
Statistics
The range
S4 General
Here are the high jump scores for two girls in metres.
Joanna
1.62
1.41
1.35
1.20
1.15
Kirsty
1.59
1.45
1.30
Find the range for each girl’s results and use this to find out who is consistently better.
Joanna’s range = 1.62 – 1.15 = 0.47
Kirsty’s range = 1.59 – 1.30 = 0.29
20-Nov-18
Created by Mr Lafferty Maths Dept

17. Created by Mr Lafferty Maths Dept
Statistics
Averages
S4 General
Now try Ex 2A
Ch5 (page 58)
20-Nov-18
Created by Mr Lafferty Maths Dept

18. Created by Mr Lafferty Maths Dept
Starter Questions
140o xo
20-Nov-18
Created by Mr Lafferty Maths Dept

19. Created by Mr Lafferty Maths Dept
Statistics
Mean from Mid interval Frequency Table
Learning Intention
Success Criteria
Construct and understand the Key-Points of a various frequency tables.
To explain how to calculate the mean from various frequency tables.
2. Calculate the mean from frequency tables.
20-Nov-18
Created by Mr Lafferty Maths Dept

20. The mean from a frequency table
Here are the results of a survey carried out among university students.
Numbers of sports played
Frequency 20 1 17 2 15 3 10 4 9 5 6
If you were to write out the whole list of results, what would it look like?
What do you think the mean would be?
20-Nov-18
Created by Mr Lafferty Maths Dept

21. Created by Mr Lafferty Maths Dept
Statistics
The mean from a frequency table
S4 General
Numbers of sports
Frequency
Number of sports
× frequency 20
0 × 20
= 0 1 17
1 × 17
= 17 2 15
2 × 15
= 30 3 10
3 × 10
= 30 4 9
4 × 9
= 36 5 3
5 × 3
= 15 6 2
6 × 2
= 12
TOTAL 76
140
20-Nov-18
Created by Mr Lafferty Maths Dept
Mean = 140 ÷ 76 = 1.84
2 sports (to the nearest whole)

22. Mid-Interval Frequency Table
Example : The test scores for a class are given below Construct a Frequency Table for the results.
Class Intervals
Mid Interval
Frequency 56
10-19
14.5
24.5
34.5
44.5
54.5
64.5 6 5
20-29
30-39 3
Lowest value = 12
40-49
50-59
60-69 6 5
Highest value = 69 1
Group data in 10’s
20-Nov-18

23. Mid-Interval Frequency Table
Class Intervals
Mid-Interval
Frequency
Mid x F
14.5 87
24.5
122.5
34.5
103.5
44.5
267
54.5
272.5
64.5
Total
10-19 6 5
20-29
30-39 3
40-49 6
50-59 5
60-69 1 26
917
Mean =
(Class interval 30-39)

24. Created by Mr Lafferty Maths Dept
Statistics
Mean from Mid interval Frequency Table
S4 General
Now try Ex 2B
Ch5 (page 59)
20-Nov-18
Created by Mr Lafferty Maths Dept

25. Created by Mr Lafferty Maths Dept
Starter Questions
138o xo
20-Nov-18
Created by Mr Lafferty Maths Dept

26. Created by Mr Lafferty Maths Dept
Scattergraphs
Construction of Scattergraphs
Learning Intention
Success Criteria
Construct and understand the Key-Points of a scattergraph.
To construct and interpret Scattergraphs.
2. Know the term positive and negative correlation.
20-Nov-18
Created by Mr Lafferty Maths Dept

27. Scattergraphs www.mathsrevision.com Construction of Scattergraph
This scattergraph shows the heights and weights of a sevens football team
Scattergraphs
Write down height and weight of each player.
Construction of Scattergraph
Bob
Tim
Joe
Sam
Gary
Dave
Jim
20-Nov-18
Created by Mr Lafferty Maths Dept

28. Created by Mr Lafferty Maths Dept
Scattergraphs
Construction of Scattergraph
When two quantities are strongly connected we say there is a
strong correlation between them.
Best fit line x x
Best fit line
Strong positive
correlation
Strong negative
correlation
20-Nov-18
Created by Mr Lafferty Maths Dept

29. Scattergraphs www.mathsrevision.com Construction of Scattergraph
Draw in the best fit line
Scattergraphs
Construction of Scattergraph
Is there
a correlation?
If yes, what kind?
Age
Price
(£1000) 3 1 2 4 5 9 8 7 6
Strong negative correlation
20-Nov-18
Created by Mr Lafferty Maths Dept

30. Created by Mr Lafferty Maths Dept
Statistics
Relative Frequency
S4 General
Now try Exercise 3
Ch5 (page 60)
20-Nov-18
Created by Mr Lafferty Maths Dept

31. Created by Mr Lafferty Maths Dept
Starter Questions
55o xo
80o
20-Nov-18
Created by Mr Lafferty Maths Dept

32. Created by Mr Lafferty Maths Dept
Statistics
Frequency Polygons
Learning Intention
Success Criteria
To explain frequency polygon graphs.
Understand the frequency polygon.
Interpret and construct frequency polygon graphs.
20-Nov-18
Created by Mr Lafferty Maths Dept

33. Statistics www.mathsrevision.com The frequency table and diagram shows
the distribution of weight in a batch of melons.
Add mid point zero values either side
Join points together and you have made frequency polygon
Join mid-point values
250
300
350
400
450
500
600
20-Nov-18
Created by Mr Lafferty Maths Dept

34. Created by Mr Lafferty Maths Dept
Statistics
Frequency Polygon
Key Points
1. Complete tables.
2. Draw frequency diagram
3. Plot mid-point values
( remember end mid-point values)
4. Join them together
20-Nov-18
Created by Mr Lafferty Maths Dept

35. Created by Mr Lafferty Maths Dept
Statistics
Frequency Polygon
S4 General
Now try Ex 4A & 4B
Ch5 (page 61)
20-Nov-18
Created by Mr Lafferty Maths Dept