In: Statistics and Probability
5. An experiment to compare the tension bond strength of polymer latex modified mortar (Portland cement mortar to which polymer latex emulsions have been added during mixing) to that of unmodified mortar resulted in ¯x = 18.12 kgf/cm 2 for the modified mortar (m=40) and ¯y = 16.87 kgf/cm 2 for the unmodified mortar (n= 32) . Let µ1, µ2 be the true average tension bond strengths for the modified and unmodified mortars, respectively. Assume that the bond strength distributions are both normal. a) Assuming that σ1 = 1.6 and σ2 = 1.4, do we have enough evidence to support the claim that true average of tension bond strengths the modified mortars is larger at level .01 b) Find a 90% confidence interval on the difference in mean batch viscosity resulting from the process change. c) How would the analysis and conclusion of part (a) change if σ1, σ2 were unknown but S1 = 1.6 and S2 = 1.4 ?.