Consumer Federation of America recently studied the relationship between tensile strength and amount of nickel in household stainless steel products. The percentage of nickel by weight (x) and the...

Consumer Federation of America recently studied the relationship between tensile strength and amount of nickel in household stainless steel products. The percentage of nickel by weight (x) and the tensile strength ( y, in MPa) were measured for each product. The data are given in the following table.

a. Find the estimated regression line, and complete the ANOVA table.

b. Compute the residuals.

 c. Carefully sketch a normal probability plot of the residuals, and interpret the graph.

d. Carefully sketch a scatter plot of the residuals versus the predictor variable. Is there any indication of a violation in the regression model assumptions?