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Problem-Solving and Data Analysis / Two-variable data: Models and scatterplots Difficulty: Medium
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The scatterplot shows the relationship between two variables, x and y .

Which of the following equations is the most appropriate linear model for the data shown?

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Explanation

Choice D is correct. The data points suggest that as the variable x increases, the variable y decreases, which implies that an appropriate linear model for the data has a negative slope. The data points also show that when x is close to 0 , y is greater than 9 . Therefore, the y-intercept of the graph of an appropriate linear model has a y-coordinate greater than 9 . The graph of an equation of the form y=a+bx, where a and b are constants, has a y-intercept with a y-coordinate of a and has a slope of b . Of the given choices, only choice D represents a graph that has a negative slope, -0.9 , and a y-intercept with a y-coordinate greater than 9 , 9.4 .

Choice A is incorrect. The graph of this equation has a positive slope, not a negative slope, and a y-intercept with a y-coordinate less than 1 , not greater than 9 .

Choice B is incorrect. The graph of this equation has a y-intercept with a y-coordinate less than 1 , not greater than 9 .

Choice C is incorrect. The graph of this equation has a positive slope, not a negative slope.