The minimum injection pressure (psi) for injection molding specimens of high amylose corn was determined for eight different specimens (higher pressure corresponds to greater processing difficulty), resulting in the following observations (from “Thermoplastic Starch Blends with a Polyethylene-Co-Vinyl Alcohol: Processability and Physical Properties,” Polymer Engr. and Sci. 1994: 17–23):

a. Determine the values of the sample mean, sample median, and 12.5% trimmed mean, and compare these values.

b. By how much could the smallest sample observation, currently 8.0, be increased without affecting the value of the sample median?

c. Suppose we want the values of the sample mean and median when the observations are expressed in kilograms per square inch (ksi) rather than psi. Is it necessary to re-express each observation in ksi, or can the values calculated in part (a) be used directly?

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15.0 13.0 18.0 14.5 12.0 11.0 8.9 8.0