A social scientist researched how the average working hours per worker, over a full year, for two different European countries changed since 1870. she created a scatter plot and found the regression line for each set of data. She then used the regression line to
create a table of values for the residuals. The scatter plots, regression equation, and residuals for the two countries are shown, where z represents the number of years since 1870 and y represents the average working hours per worker over a full year.