US federal government was evaluating how total traffic fatalities (y) are impacted by:

1. vehicle miles travelled in billions (x1),
2. unemployment rate in percent (x2)
3. percentage of population aged between 14 to 24 and (x3)
4. state population in hundred thousand (x4)

The government agency used 1200 observation to run a regression with the following results:

SUMMARY OUTPUT Regression Statistics Multiple R 0.935 R Square 0.875 Adjusted R Squ 0.874 Standard Error 311.582 Observations 1200.000 ANOVA of SS MS F Significance F Regression 4.000 810545292.022 202636323.005 2087.245 0.000 Residual 1195.000 116014342.325 97083.132 Total 1199.000 926559634.347 Coefficients Standard Error t Stat P-value Lower 95% Upper 95% Intercept -1116.558 80.838 -13.812 0.000 -1275.159 -957.958 X Variable 1 11.133 0.837 13.307 0.000 9.491 12.774 X Variable 2 15.696 4.951 3.170 0.002 5.982 25.409 X Variable 3 73.108 5.484 13.331 0.000 62.348 83.867 X Variable 4 5.394 0.704 7.666 0.000 4.014 6.775