Problem 12.4 The effect of four different mixing techniques on the compressive strengths of concrete is investigated and the following data are collected. Mixing technique Compressive strength 1 2868 2913 2844 2887 2 3250 3262 3110 2996 3 2838 3049 3030 2832 4 2847 2721 2530 2598 Does the mixing technique affect the compressive strength? State the null hypothesis and the alternative hypothesis. Construct the ANOVA table. Test the null hypothesis at the level α = 0.05. Summarize your conclusions. Save your computations.