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Introduction The points in the scatter plot provides a mean of reasoning out where the best fit should pass. The points can only allow us to estimate the value of a given point within the range of values given. However, our concern may be to determine the value of the independent variable outside the given range of values. This is simply predicting the value of the independent variable for a given value of the dependent variable outside the range of the given values. Thus can only be done by the use of an equation of the line of the best fit.
Vocabulary: Scatter plot It is a graph composed of points representing the relationship between data of two related variables Line of the best fit It is the line in a scatter plot that best represents the points plotted
Predicting the values We first determine the equation of the line of the best fit. We substitute for the independent variable (using the given value) to determine the predicted value of the dependent variable. Example 1 The table below shows the performance of students and the number of hours spent reading every weekend.
Determine the equation of the best fit. Estimate the performance of a student who takes 2.5 hours every weekend reading. Solution Upon drawing the scatter plot and determining the line of the best fit, we have the following graph.
homework The graph below shows the price of a half an acre of land over some time.
homework Identify any two points that lie on the line Using the points, determine the equation of the line of the best fit Using the equation predict the possible price of the piece of land in 2017.
