1. Revision - Statistical Data – Types of Graphs, Charts, Tables etc and what to look out forx
Straight Line Graphs
y = mx + c
Pie Charts x
Positive correlation
Negative correlation
No correlation
Reading scatter graphs axis relationships y 28
122 x
Facts
Right angle = 90º
360º in a circle 5 3
From the above facts you will be able to find angle X 1 x
Example Given y = 2x + 3, then plot table as shown below,
Then do the graph shown above
Typical Question might say
180 pupils in a school, and pie
Chart consists of the following
H = hockey
F = football
R = rugby
N = netball
Find the number of pupils that are playing football x
Line Graphs
Bar Chart
Frequency Polygon 28
122 F N R H x y 1 2 3 -3 -2 -1 5 7 9
Frequency Table – Mid Values
Estimating the Mean
MEAN – (or average value)
To find the mean first add all the individual numbers to find total and then divide by the number
MODE – means most COMMON number
MEDIAN – median is the middle number
RANGE – means range from smallest to largest. To find the range take the smallest number from the largest
Note – When finding mode ,median mean, and range ,first place numbers in ascending order if they are out of order. This will help clarify the solution to finding the values.
Example - 2,3,4,5,5,7,8,9,11
MEAN (average value) is found by
= 54/9 = 6
MODE , most common value is 5, MEDIAN, middle value is 5
RANGE is between 2 and 11, therefore
11-2 = 9 10 20 2 7 1 3 6 9 30 40 4
Mean = 22 = 17
Key Code
= 352/16
Mean
Mode is 21 (being the most common number)
Median – Middle numbers are 21and 22
so median is 21.5
Range – 41 – 2 = 39
Stem / Leaf Table
First find F – see first example to find F. 180 pupils means 360/180 gives 2º per pupil. Knowing F degrees, then you can work out number in F
Height cm
0 <h ≤10
10 <h ≤20
20 <h ≤30
30 <h ≤40
40 <h ≤50
mid point 5 15 25 35 45
freq 2 4 8 1
Total 10 60
200
175 20
490
Totals
Estimate the Mean by
1st find mid-values
Add up frequency totals
Mid- values x frequency to obtain total
Add up all totals to obtain grand total
Estimate Mean is 490 /20 = 24.5
Pictorial type, example display
shown below