Nine Adults Were Selected at Random from Among Those Working

Nine adults were selected at random from among those working full time in the town of Workington.
Each person was asked the number of years of college education they had completed and was also asked to rate
their job satisfaction on a scale of 1 to 10.
The pairs of data values area plotted in the scatterplot below. The four points in the lower left corner correspond to employees from company A and the five points in the
upper right corner correspond to employees from company B.
a. Using the pairs of values for all 9 points, find the equation of the regression line.
b. Using only the pairs of values for the four points in the lower left corner, find the equation of the regression
line.
c. Using only the pairs of values for the five points in the upper right corner, find the equation of the regression
line.
d. Compare the results from parts a, b, and c.