1. Warm-Up Graph each point in the same coordinate plane. 1) A(1,400) 4 minutes 2) B(3,300) 3) C(6,150)4) D(8,50) 5) Suppose that a line were drawn to connect the four points. Would its slope be positive or negative?

2. 1.5 Scatter Plots and Least-Squares Lines 1.5 Scatter Plots and Least-Squares Lines Objectives: Create a scatter plot and draw an informal inference about any correlation between the variables Use a graphics calculator to find an equation for the least-squares line and use it to make predictions or estimates

3. Scatter Plot Chicken Pox in the United States x y 20 40 60 80 100 120 140 160 180 123 4 5 6 # of years after 1988 Chicken Pox in the U.S. YearReported Cases (in thousands) 1989185.4 1990173.1 1991147.1 1992158.4 1993134.7 1994151.2 Reported cases (1000’s)

4. Correlation x y x y x y positive correlation negative correlation no reliable correlation

5. Least-Squares Line 2 42 68 10 4 6 8 (line that best fits the data)

6. Example 1 Create a scatter plot for the data shown below. Describe the correlation. Then find and graph an equation for the least-squares line. x02367912 y14192226 3238

7. Correlation and Prediction x y x y perfect negative correlation perfect positive correlation x y no reliable correlation r = -1r = 0r = 1

8. Example 2 The table below shows the number of juniors enrolled in Algebra 2 at LHS in six of the last 7 years. The number for the third year has been misplaced. Estimate the number of students enrolled in Algebra 2 in the third year. year124567 #33294543 61

9. Homework p.40 #9-11,13,15-20,22 *you need a graphing calculator for this assignment