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Line of Best Fit

1.11 Bivariate Home | Assessment Criteria | Ask a Question | Make a Plan | Collecting Data | Cleaning Data | Making Scatterplots | Describing Scatterplots | Outliers | Line of Best Fit | Population Inference | Conclusion | Revision

9



Adding a line-of-best-fit in Excel

Use the equation of the line-of-best-fit to predict 'y' values from a 'x' value

Use the equation of the line-of-best-fit to predict 'x' values from a 'y' value

Class notes, Blank notes  

 

A line can be drawn to ‘fit’ the relationship

Using Excel – right click on a data point and 'Add Trend line' and tick the ‘show equation’ box near the bottom

The equation line can then be used to predict ‘y’ and ‘x’ values

 

Eg
If Variable ‘A’ = 10, predict a value for ‘B’

      y = 1.026x - 0.3249

so  B = 1.026×10 - 0.3249 = 9.9351  which should be rounded sensibly

     B = 9.9 and remember units

 

 

Predicting ‘x’ from a given ‘y’ is involves solving an equation.

Eg If Variable ‘B’ = 14, predict a value for ‘A’

      y = 1.026x - 0.3249

 so  14 = 1.026×A - 0.3249

14.3249 = 1.026×A

13.96189 = A

Round sensibly  A = 14

Check the if the solution matches the graph

 

Examples

1) If a student had a Maths score of 14, predict their English Score.

 

2) If a student had a Maths score of 6, predict their English Score.

 

3) If a student had a English score of 8, predict their Maths Score.

 

4) If a student had a English score of 16, predict their Maths Score.

 

5) How accurate are these predictions?

 

 

 

 

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