Maths Revision :
Multiplicative Change
Representing Data
Working in the Cartesian plane
Coordinates in four quadrants
Recognise and use the line y=x
Recognise and use the lines y=kx
Draw and interpret a scatter graph.
Linear Correlation
The line of best fit
Draw and interpret scale diagrams
Understand Scale Factor
Direct Proportion
The data forms information pairs for the scatter graph
Not all data has a relationship
Negative Correlation
Positive Correlation
The line of best fit DOES NOT need to
go through the origin
It is always a straight line.
No Correlation
There is no relationship between the two variables
As one variable increases the other variable decreases
As one variable increases so does the other variable
(0,a) Will be always be a point
on the y axis. (a can be any number)
(a.0) Will be always be a point
on the x axis. (a can be any number)
Examples of coordinates on the line y=x - (3,3), (8,8)
This means that the x and y coordinate have the same value
The value of k changes the steepness
of the line
The line will always go
through (0,0)
As one variable changes the other changes at
the same rate.
Sometimes this is the easiest way if you work out how much one unit is worth first
This is a multiplicative change
The car image is 10cm
A picture of a car is drawn with a scale of 1:30
For every 1cm on my image is
30cm in real life
Image - 1:30 - Real life - 10:300
Use corresponding sides to calculate a scale factor
Scale factor can also
be calculated by:
Bigger corresponding side
(over)
Smaller corresponding side
Ratio and Scale
Finding a value given 1:n (or n:1)
Order is Important
Ratio 1:n (or n:1)
Show the ratio 4:20 in the ratio of 1:n
This is asking you to cancel down until the part
indicated represents 1
The ratio has to be written in the same order as the information is given
For every dog there are two cats - Dogs:Cats - 1:2
Inside a box are blue and red pens in the ration 5:1. If there are 10 red pens how many blue pens are there
4:20 = 1:5
5:1 = ?:10
1 x 10 = 10. 5 x 10= 50
5:1 = 50:10
Ratio as a fraction
Trees : Flowers = 3 : 7
3 parts trees + 7 parts flowers = 10 parts whole
Parts for trees - 3/10. Parts for flowers - 7/10
Interpret maps with scale factors
The conversion between measurements - Used for mapping (sometimes)