A researcher, wanted to understand the linear relationship between household annual water bill ($), the number of people per household and the capacity of a backyard water tank (litres) of that household. Only households with water tanks were sampled. They took a random sample and used Excel to create the following regression output.

SUMMARY OUTPUT Regression Statistics Multiple R 0.856 R Square 0.734 Adjusted R Square 0.657 Standard Error 1390.792 Observations 10 ANOVA SS MS F Significance F Regression 37276493.84 18638247 9.636 0.010 Residual 13540116.16 1934302.3 Total 50816610 Coefficients Standard Error t Stat P-value Lower 95% Upper 95% Intercept -12.636 721.713 -0.018 0.987 -1719.216 1693.945 People per household 531.258 122.887 4.323 0.003 240.677 821.838 Backyard water tank capacity (litres) -0.280 0.114 -2.453 0.044 -0.550 -0.010