he commercial division of a real estate firm is conducting a regression analysis of the relationship between , annual gross rents (in thousands of dollars), and , selling price (in thousands of dollars) for apartment buildings. Data were collected on several properties recently sold and the following computer output was obtained. ANOVA df SS MS F Significance F Regression 1 41587.1 Residual 7 Total 8 51984.5 Coefficients Standard Error t Stat P-value Intercept 20.000 3.2213 6.21 Annual Gross Rents 7.220 1.3627 5.29 a. How many apartment buildings were in the sample