1. Learning Intention
Revise the statistical measures
mean, median, mode
range, upper and lower quartiles, interquartile range
displays (graphs) which are good for showing these measures
Please write this in your notes book

2. Find the mean of the numbers 4, 0, 3, 11 and 6.
4 0 3 11 6 Add up and divide by the number of scores.
x
5
24
5
4 .8

3. Find the median of these sets of numbers:
a 4, 8, 3, 11, 6
b 3, 5, 7, 4, 9, 2
c 4, 7, 7, 3, 9, 8
a 3, 4, 6, 8, 11 First put the numbers in order.
Work in from the ends to find the middle.
The median is 6
b 2, 3, 4, 5, 7, 9 First put the numbers in order.
Work in from the ends to find the middle.
The median is half way between 4 and 5.
The median is 4.5
c 3, 4, 7, 7, 8, 9 First put the numbers in order.
Work in from the ends to find the middle.
There are two middle numbers, both of
The median is 7 which are the same.

4. Find the mode of these sets of numbers:
a 6, 9, 4, 5, 7, 2, 7, 5, 7, 3
b 8, 9, 3, 8, 9, 4, 7
c 6, 12, 11, 9, 10
a 6, 9, 4, 5, 7, 2, 7, 5, 7, 3 Which number is most common?
The mode is 7.
b 8, 9, 3, 8, 9, 4, 7 Which number is most common?
There are two modes, 8 and 9.
c 6, 12, 11, 9, 10 Which number is most common?
There is no mode.

5. Calculate the range of the numbers 10, 20, 2, 25, 11, 18, 23.
The largest value = 25
The smallest value = 2
Range = 25 – 2
= 23

6. Find the lower and upper quartiles for each of
12 14 17 20 21 21 21 26
12 14 17 20 21 21 21 26 Find the median.
The median is 20.5
Find the median of the lower group.
The low group is 12, 14, 17, 20 which has a median of 15.5
Find the median of the high group.
The high group is 21, 21, 21, 26 which has a median of 21
LQ = 15.5
UQ = 21
The interquartile range = 21 – 15.5
= 5.5

7. Find the lower and upper quartiles for each of
0 2 3 5 6 8 9 9 10 12
0 2 3 5 6 8 9 9 10 12 Find the median.
The median is 7
Find the median of the lower group.
The low group is 0, 2, 3, 5, 6 which has a median of 3
Find the median of the high group.
The high group is 8, 9, 9, 10, 12 which has a median of 9
LQ = 3
UQ = 9 IQR = 9 - 3
=6

8. Find the lower and upper quartiles for each of
45 47 52 61 77
45 47 52 61 77 Find the median.
The median is 52
Discard 52 so that the remaining numbers form two equal groups.
Find the median of the lower group.
The low group is 45, 47 which has a median of 46
Find the median of the high group.
The high group is 61, 77 which has a median of 69
LQ = 46
UQ = 69 IQR = 69 - 46
= 23

9. Think, pair, share
What display types (graphs) could you
use to display the
Median, Range, UQ, LQ and IQR ?

10. Geogebra
Box Plot vs Dot Plot per FT p.129 RHS
Box Plot vs Histogram per FT p.128 RHS not really covered
Box plots (comparison)
Mean vs median vs spread

11. This exercise is to be
completed on refill and
handed in for marking.

12. Using the Graphics Calculator to find statistics
Use the Graphics calculator to find the median, range, upper quartile, lower
quartile and inter-quartile range.
Main menu: Stat
Delete lists: (F6), DEL-A (F4), YES (F1)
(just in case there is already data there)
Enter data into list: data value, EXE (after each data value)
Calculate statistics: > (more options) (F6), CALC (F2),
SET (F6) (check for top option 1VAR XList: List 1)
1VAR (F1)
The symbols for:
Median = Med Range = maxX—minX
lower quartile = Q1 upper quartile = Q3
inter-quartile range = Q3—Q1

13. Using the Graphics Calculator to graph statistics
Once you have the five point summary, use the GC to graph
Main menu: Stat
The data and stats are is still there
Graph Statistics GRPH (F1),
SET (F6), down arrow to Graph Type
Select Box (may need to > for more options) EXE
GPH1 will display box and whisker