1. SCATTERGRAPHS Plot the points Draw in the line of best fit
Select two points which lie on the line
Find the gradient
Hence find the equation of the line

2. x 2 3 4 5 6 7 8 y 10 11 14 15 17 x y
Plot the points

3. x 2 3 4 5 6 7 8 y 10 11 14 15 17 x y
Draw the line of best fit

4. x 2 3 4 5 6 7 8 y 10 11 14 15 17 Select two points on the line
m = y2 – y1
x2 – x1
Find the gradient
m = y2 – y1 = 15 – 10
x2 – x
m = 1

5. x 2 3 4 5 6 7 8 y 10 11 14 15 17 Find the equation of the line
y = mx + c
y = 1×x + c
But (7,15) lies on the line
So 15 = 1×7 + c
And c = 8
Equation of line is y = x + 8

6. SCATTERGRAPHS Plot the points Draw in the line of best fit
Select two points which lie on the line
Find the gradient
Hence find the equation of the line

7. x 50 52 55 56 58 61 62 y 20 19 18 17 15 x y
Plot the points

8. x 50 52 55 56 58 61 62 y 20 19 18 17 15 Draw in the line of best fit y

9. x 50 52 55 56 58 61 62 y 20 19 18 17 15 Select two points on the line
m = y2 – y1
x2 – x1
Find the gradient
m = y2 – y1 = 18 – 17
x2 – x
m = - 1/2

10. x 50 52 55 56 58 61 62 y 20 19 18 17 15 Find the equation of the line
y = mx + c
y = -1/2×x + c
But (56,18) lies on the line
So 18 = -1/2×56 + c
And c = 46
Equation of line is y = -1/2x + 46