The sterplot shows the relationship between two variables, x and y . A line of best fit is also shown.

Question

The sterplot shows the relationship between two variables, $x$ and $y$ . A line of best fit is also shown.

Which of the following is closest to the slope of the line of best fit shown?

Accepted Answer

Choice B is correct. A line of best fit is shown in the sterplot such that as the value of x increases, the value of y decreases. Thus, the slope of the line of best fit shown is negative. The slope of a line passing through two points, x 1 , y 1 and x 2 , y 2 , can be calculated as y 2 - y 1 x 2 - x 1 . The line of best fit shown passes approximately through the points 1 , 12 and 11 , 4 . Substituting 1 , 12 and 11 , 4 for x 1 , y 1 and x 2 , y 2 , respectively, in y 2 - y 1 x 2 - x 1 gives 4 - 12 11 - 1 , which is equivalent to - 8 10 , or - 0.8 . Therefore, of the given choices, - 0.8 is closest to the slope of the line of best fit shown. Choice A is incorrect and may result from conceptual or calculation errors. Choice C is incorrect. The line of best fit shown has a negative slope, not a positive slope. Choice D is incorrect. The line of best fit shown has a negative slope, not a positive slope.

Question 9b172c