For each residual plot below, decide on whether the usual assumptions: "Y; = ,80 +51% + 6;,13 = 1, . .. ,n,; independent N(0.02) random variables" of simple linear regression are valid or not. If some assumptions seem invalid, choose the options(s) which indicate the most obvious departures from the model assumptions. Note : For a small sample, the normality assumption cannot be "proved", but it can be "violated" ifthere is an extreme residual (outlier). Part a] fiii 4197. . t I i a yaxis has residual, x-axis has xvariable with values 1,2,...,1U. (Click on graph to enlarge) Which is/are the best answer(s) for the residual plot (a)? l:l A. assumptions seem reasonable B. the normality assumption is invalid l:l C. linear relation assumption is invalid l:l D. constant variance assumption is invalid l:l E. None ofthe above Part b] yaxis has residual, xaxis has xvariable with values 1,2,...,10. (Click on graph to enlarge) Which is/are the best answer(s) for the residual plot (b)? 1:1 A. linear relation assumption is invalid 1:1 B. the normality assumption is invalid 1:1c. assumptions seem reasonable D. constant variance assumption is invalid E. the residuals show a pattern 1:1 F. None ofthe above Part c] _________ y-axis has residual, x-axis has xvariable with values 1,2,...,1U. (Click on graph to enlarge) Which islare the best answer(s) for the residual plot (c)? l:l A. linear relation assumption is invalid B. the normality assumption is invalid Cl C. the residuals show a pattern l:l D. assumptions seem reasonable E. constant variance assumption is invalid l:l F. None ofthe above