In the article Bactericidal Properties of Flat Surfaces and Nanoparticles Derivatized

Chapter 5, Problem 14

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In the article “Bactericidal Properties of Flat Sur- faces and Nanoparticles Derivatized with Alkylated  Polyethylenimines” (J. Lin, S. Qiu, et al., Biotechnol- ogy Progress, 2002:1082–1086), experiments were  described in which alkylated polyethylenimines were attached to surfaces and to nanoparticles to make them  bactericidal. In one series of experiments, the bactericidal efficiency against the bacterium E. coli was compared for a methylated versus a non methylated polymer. The mean percentage of bacterial cells killed with  the methylated polymer was 95 with a standard deviation of 1, and the mean percentage of bacterial cells  killed with the non methylated polymer was 70 with a standard deviation of 6. Assume that five independent measurements were made on each type of polymer. Find a 95% confidence interval for the increase in bactericidal efficiency of the methylated polymer.