Ishikawa et al. (Journal of Bioscience and Bioengineering, 2012) studied the adhesion of various biofilms to solid surfaces for possible use in environmental technologies. Adhesion assay is conducted by measuring absorbance at A590. Suppose that for the bacterial strain Acinetobacter, five measurements gave readings of 2.69, 5.76, 2.67, 1.62 and 4.12 dyne-cm^2. Assume that thepopulationis normal, and populationstandard deviation is known to be 0.66 dyne-cm^2. Requird:
a. Find a 95% confidence interval for the mean adhesion.(b)If the scientists want the confidence interval to be no wider than 0.55 dyne-cm^2, how many observations shouldthey take?
b. If the scientists want the confidence interval to be no wider than 0.55 dyne-cm^2, how many observations should they take? (Note that, the width of the confidence interval is two times the margin error E, so E = 0.55/2).
c. Find the 95% lower and upper confidence bound for the mean adhesion.
d. Now, suppose the population standard deviation is unknown, redo part (a).