The compressive strength of concrete is known to be affected by three factors: p

Question

The compressive strength of concrete is known to be affected by three factors: percentage fines in the aggregate, ratio of cement aggregate (C & A ratio) in the mix, and percentage by volume of water added to the mix. The following results were obtained in an experiment to determine the best levels of these factors to obtain the maximum compressive strength. Two trails were performed at each treatment combination. Find the effects of the factors and the significance of the factors, and determine the best combination of the factor levels.

Explanation / Answer

Taking low as 0 and high as 1 and average of the two experiments was used
multiple regression analysis was done using excel

SUMMARY OUTPUT Regression Statistics Multiple R 0.986006122 R Square 0.972208073 Adjusted R Square 0.951364128 Standard Error 20.89258242 Observations 8 ANOVA df SS MS F Significance F Regression 3 61078 20359.33333 46.64222986 0.001434746 Residual 4 1746 436.5 Total 7 62824 Coefficients Standard Error t Stat P-value Lower 95% Upper 95% Lower 95.0% Upper 95.0% Intercept 529.5 14.7732867 35.84171963 3.61697E-06 488.4827804 570.5172196 488.4827804 570.5172196 C/A ratio 165 14.7732867 11.16880782 0.000365816 123.9827804 206.0172196 123.9827804 206.0172196 Moisture 55 14.7732867 3.722935939 0.020422177 13.98278045 96.01721955 13.98278045 96.01721955 Fines -17 14.7732867 -1.150725654 0.313955369 -58.01721955 24.01721955 -58.01721955 24.01721955

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