Lines of best fit.
Sometimes one or two results may be way off the mark for some inexplicable reason. These results are ignored when drawing the graph. Sometimes the graph is represented by a line of best fit. It can be straight or curved. That is to say a line that comes close to as many points as possible, without necessarily passing through all the points, is drawn.

The graph on the left shows the distance an ant is from its as it travels in a straight path away from its nest. Distance is plotted against time. A line of best fit is drawn. Note that it does not go through all the points but comes close to as many points as possible. Sometimes a straight line may not be the best option, as is obvious when you click to see the graph. A curved line might be best as a line of best fit.

  
 
Ant population seconds after spraying with Begong insecticide
Time(seconds)
Number of ants
0
150,000
15
148,025
30
147,115
45
149,085
60
146,522
75
146,090
90
145,000
105
145,963
120
145,660


Consider an experiment where Begong insecticide was tested on an ant colony. A three second spray of Begong was applied to the nest and the ants that were still alive were counted every 15 seconds. The table on the left represents the data collected.

Graph the results and draw a line of best fit.
Solution

Is there any data that should be ignored when graphing the data.

Solution

A car travels in a straight line away from home. The distance is recorded every 15 minutes and the results are presented in the table on the right.

Plot a line of best fit to represent the data.

Solution
Distance versus time
Time(minutes)
Distance (km)
0
0
15
15
30
25
45
105
60
180
75
260
90
350
105
490
120
500

Continue

Continue with an exercise
Chalk Vinegar