In the given sterplot, a line of best fit for the data is shown. The sterplot has 10 data points.

Question

In the given sterplot, a line of best fit for the data is shown.

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

Accepted Answer

Choice C 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. It follows that the slope of the line of best fit shown is negative. The slope of a line in the xy -plane that passes through the 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 0 , 8 and 10 , 1 . Substituting 0 , 8 for x 1 , y 1 and 10 , 1 for x 2 , y 2 in y 2 - y 1 x 2 - x 1 yields the slope of the line being approximately 1 - 8 10 - 0 , which is equivalent to - 7 10 , or - 0.7 . Therefore, of the given choices, - 0.7 is the closest to the slope of this line of best fit. Choice A is incorrect. The line of best fit shown has a negative slope, not a positive slope. Choice B is incorrect. The line of best fit shown has a negative slope, not a positive slope. Choice D is incorrect and may result from conceptual or calculation errors.

Question in-the