Question:

The data are given on the attached file abrasion.

The hardness and the tensile strength of rubber affect its resistance to abrasion. Thirty samples of rubber are tested for hardness and tensile strength. Each sample was subjected to steady abrasion for a certain fixed period of time, and the loss of rubber was measured.

Develop a model that relates the abrasion loss to hardness and tensile strength.

Construct scatter plots of abrasion loss against hardness and tensile strength. Fit appropriate regression models, obtain and interpret the estimates of the coefficients, calculate the ANOVA table, and discuss the adequacy of the model fit. Use your model(s) to obtain a 95% confidence interval for the mean abrasion loss for rubber with hardness 70 and tensile strength 200.