Which of the following could be the equation for a line of best fit for the data shown in the scatterplot above? 

Choice A is correct. The data show a strong linear relationship between x and y. The line of best fit for a set of data is a linear equation that minimizes the distances from the data points to the line. An equation for the line of best fit can be written in slope-intercept form, y = mx + b, where m is the slope of the graph of the line and b is the y-coordinate of the y-intercept of the graph. Since, for the data shown, the y-values increase as the x values increase, the slope of a line of best fit must be positive. The data shown lie almost in a line, so the slope can be roughly estimated using the formula for slope, \(m=\frac{y_{2}-y_{1}}{x_{2}-x_{1}}\). The leftmost and rightmost data points have coordinates of about (1, 4) and (8, 26), so the slope is approximately \(\frac{26-4}{8-1}=\frac{22}{7}\), which is a little greater than 3. Extension of the line to the left would intersect the y-axis at about (0, 1). Only choice A represents a line with a slope close to 3 and a y-intercept close to (0, 1). 
Choice B is incorrect and may result from switching the slope and y-intercept. The line with a y-intercept of (0, 3) and a slope of 0.8 is farther from the data points than the line with a slope of 3 and a y-intercept of (0, 0.8). Choices C and D are incorrect. They represent lines with negative slopes, not positive slopes.