Final answer:
The equation of the line with a slope of 3 and a y-intercept of 9 is y = 3x + 9. Plotting data and adding a regression line requires using a calculator's regression function.
Step-by-step explanation:
Finding the Equation of a Line
To find the equation of a line in slope-intercept form, we need to determine the line's slope (m) and y-intercept (b). According to the information provided, the y-intercept is 9, which means when x is 0, y is 9. The slope is given as 3, which means for each increase of 1 on the x-axis there is a rise of 3 on the y-axis. Using this data, we can construct the equation of the line in slope-intercept form (y = mx + b) as y = 3x + 9.
If data is provided, you would plot the data points on the coordinate grid and draw the regression line that best fits the data. To perform a regression analysis and find the least squares regression line, you would use the regression function on a calculator. You can then add this line to your scatter plot to visualize the relationship between the variables.