Solve this problem by Minitab program.

3.7. The tensile strength of Portland cement is being stud- ied. Four different mixing techniques can be used economi- cally. A completely randomized experiment was conducted and the following data were collected: Mixing Technique Tensile Strength (lb/in?) 1 3105 2976 2841 2866 2 3179 3276 2951 3126 3 2779 2876 2961 3026 4 2576 2676 2576 2741 solve this problem by Minitab program (a) Test the hypothesis that mixing techniques affect the strength of the cement. Use a = 0.05. (c) Use the Fisher LSD method with a = 0.05 to make comparisons between pairs of means. (d) Construct a normal probability plot of the residuals. What conclusion would you draw about the validity of the normality assumption? (e) Plot the residuals versus the predicted tensile strength. Comment on the plot. (f) Prepare a scatter plot of the results to aid the interpre- tation of the results of this experiment