A publisher of college textbooks conducted a study to relate profit per text y to cost of sales x over a 6-year period when its sales force (and sales costs) were growing rapidly. These inflation-adjusted data (in thousands of dollars) were collected: Expecting profit per book to rise and then plateau, the publisher fitted the model to the data. What conclusions can you draw from the accompanying residual plots?

Question

A publisher of college textbooks conducted a study to relate profit per text y to cost of sales x over a 6-year period when its sales force (and sales costs) were growing rapidly. These inflation-adjusted data (in thousands of dollars) were collected:  Expecting profit per book to rise and then plateau, the publisher fitted the model  to the data. What conclusions can you draw from the accompanying residual plots?

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The Answer of A publisher of college textbooks conducted a study to relate profit per text y to cost of sales x over a 6-year period when its sales force (and sales costs) were growing rapidly. These inflation-adjusted data (in thousands of dollars) were collected:  Expecting profit per book to rise and then plateau, the publisher fitted the model  to the data. What conclusions can you draw from the accompanying residual plots?

A Publisher of College Textbooks Conducted a Study to Relate