13,14,15 25,26,27,28

19. USING TOOLS Use a ruler or a } astick to find the In Exercises 13 and 14, make a scatter plot of the data. heights and arm spans of five people. Tell whether x and y show a positive, a negative, or no a. Make a scatter plot using the data you collected correlation. Then draw a line of fit for the data. 13. X 3.1 2.2 3.7 3.9 1.5 5 2.7 2.0 2 2.5 b. Interpret the slope and y-intercept of the line of 3 2 y 0 2 0 2 20. THOUGHT PROVOKING A line of fit for a scatter ph is given by the equation y = 5x + 20. Describe a G 14. X 3 4 5 6 7 8 9 10 real-life data set that could be represented by the Learnin HSF-LE 67 50 33 25 21 19 4 scatter plot. 67 HSS- I HSS-ID HSS-ID 15. MODELING WITH MATHEMATICS The table shows the 21. WRITING When is data best displayed in a scatter plot, rather than another type of display, such as a be HSS-ID world birth rates y (number of births per 1000 people) HSS-ID x years since 1960. (See Example 3.) graph or circle graph? HSS- 10 X 0 10 20 30 40 50 22. HOW DO YOU SEE IT? The scatter plot shows part of y 35.4 33.6 28.3 27.0 22.4 20.0 a data set and a line of fit for the data set. Four data points are missing. Choose possible coordinates for a. Write an equation that models the birthrate as a these data points. function of the number of years since 1960. Ay b. Interpret the slope and y-intercept of the line of fit. 120 16. MODELING WITH MATHEMATICS The table shows 80 the total earnings y (in dollars) of a food server who works x hours. 40 X 0 2 3 4 5 6 8 12 16 20x y 0 18 40 62 77 85 113 a. Write an equation that models the server's earnings as a function of the number of hours the 23. REASONING A data set has no correlation. Is it server works. possible to find a line of fit for the data? Explain. b. Interpret the slope and y-intercept of the line of fit. 24. ANALYZING RELATIONSHIPS Make a scatter plot of the data in the tables. Describe the relationship 17. OPEN-ENDED Give an example of a real-life data set between the variables. Is it possible to fit a line to that shows a negative correlation. the data? If so, write an equation of the line. If not, explain why. 18. MAKING AN ARGUMENT Your friend says that the data in the table show a negative correlation because X - 12 the dependent variable y is decreasing. Is your friend -9 -7 -4 -3 correct? Explain. y 150 76 50 15 10 x 14 12 10 8 6 4 2 X 2 5 y 4 6 0 9 -1 15 -2 5 22 37 52 90 226 Maintaining Mathematical Proficiency Reviewing what you learned in previous grades and lessons Evaluate the function when x = -3, 0, and 4. (Section 3.3) 25. g(x) = 6x 27. f ( x) = 5x - 8 26. h(x) =-10x 28. v(x) = 14 - 3x 200 Chapter 4 Writing Linear Functions