Ch 15: Mastery Assignment - Multiple Regression O Zi (yi - bo - b2x2 i - b4x4i - bsxsi ) O Zi(yi - bo - box3i - bax4i - bsxsi) O zi(yi - vi) Using the least-squares criterion, the researcher obtained the following estimated multiple regression equation: y = 1,087 + 20x3 + 48x4 + 16x5 The coefficient 48 in the estimated multiple regression equation just given is an estimate of the change in average printer sales in a given month (in thousands of dollars) corresponding to a change in advertising spending when * of the other independent variables are held constant. If the advertising spending increases by 6 units under this condition, you expect printer sales to increase on average by an estimated amount of