How do I draw scatter plots and find

• How do I draw scatter plots and find equations of best-fitting lines?

7. 1 Draw Scatter Plots and Best-Fitting Lines Example 1 Describe and estimate correlation coefficients Describe the data as having a positive correlation, a negative correlation, or approximately no correlation. Tell whether the correlation coefficient for the data is closest to -1, -0. 5, 0, 0. 5, or 1. a. Solution negative correlation. a. The scatter plot shows a strong _____ So, the best estimate given is r = ____.

7. 1 Draw Scatter Plots and Best-Fitting Lines Example 1 Describe and estimate correlation coefficients Describe the data as having a positive correlation, a negative correlation, or approximately no correlation. Tell whether the correlation coefficient for the data is closest to -1, -0. 5, 0, 0. 5, or 1. b. Solution positive correlation. b. The scatter plot shows a weak _____ So, r is between ___ and ___, but not too close to either one. The best estimate given is r = _____.

7. 1 Draw Scatter Plots and Best-Fitting Lines Checkpoint. For the scatter plot, (a) tell whether the data has a positive correlation, a negative correlation, or approximately no correlation, and (b) tell whether the correlation coefficient for the data is closest to -1, -0. 5, 0, 0. 5, or 1. 1. a. positive correlation b. 1

7. 1 Draw Scatter Plots and Best-Fitting Lines Checkpoint. For the scatter plot, (a) tell whether the data has a positive correlation, a negative correlation, or approximately no correlation, and (b) tell whether the correlation coefficient for the data is closest to -1, -0. 5, 0, 0. 5, or 1. 2. a. approximately no correlation b. 0

7. 1 Draw Scatter Plots and Best-Fitting Lines Example 2 Approximate the best-fitting line The table below gives the number of people y who attended each of the first seven football games x of the season. Approximate the bestfitting line for the data. x 1 2 3 4 5 6 7 y 722 763 772 826 815 857 897 900 850 800 750 700 650 0 scatter plot 1. Draw a _____. 2. Sketch a best-fitting line. 1 2 3 4 5 6 7 3. Choose two points on the line. For the scatter plot 722 and (2, 750 shown, you might choose (1, ___). 4. Write an equation of the line. The line passes through the two points has a slope of:

7. 1 Draw Scatter Plots and Best-Fitting Lines Example 2 Approximate the best-fitting line The table below gives the number of people y who attended each of the first seven football games x of the season. Approximate the bestfitting line for the data. 900 x 1 2 3 4 5 6 7 850 800 y 722 763 772 826 815 857 897 750 700 Use the point-slope form to write the equation. 650 0 An approximation of the best-fitting line is 1 2 3 4 5 6 7

7. 1 Draw Scatter Plots and Best-Fitting Lines Checkpoint. Complete the following exercise. 3. The table gives the average class score y on each chapter test for the first six chapters x of the textbook. x y 1 84 2 83 3 86 4 88 5 87 a. Approximate the best-fitting line for the data. 6 90 92 90 88 86 84 82 0 1 2 3 4 5 6 7

7. 1 Draw Scatter Plots and Best-Fitting Lines Checkpoint. Complete the following exercise. 3. The table gives the average class score y on each chapter test for the first six chapters x of the textbook. x y 1 84 2 83 3 86 4 88 5 87 6 90 b. Use your equation from part (a) to predict the average class score on the chapter 9 test. 92 90 88 86 84 82 0 1 2 3 4 5 6 7

7. 1 Draw Scatter Plots and Best-Fitting Lines Pg. 260, 7. 1 #1 -13