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 Science, 1994: 17-23):

15.0 13.0 18.0 14.5 12.0 11.0 8.9 8.0

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

reexpress each observation in ksi, or can the values calculated

in part (a) be used directly? [Hint: 1 kg 2.2 lb.]