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-cm2. Assume that the population is normal, and population standard deviation is known to be 0.66 dyne-cm2. (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-cm2, how many observations should they take