Acrylic bone cement is commonly used in total joint replacement to secure the artificial joint. Data on the force (measured in Newtons, N) required to break a cement bond under two different temperature conditions and in two different mediums appear in the accompanying table. (These data are consistent with summary quantities appearing in the paper “Validation of the Small-Punch Test as a Technique for Characterizing the Mechanical Properties of Acrylic Bone Cement”

(Journal of Engineering in Medicine [2006]: 11– 21).)

Temperature Medium Data on Breaking Force 22 degrees Dry 100.8, 141.9, 194.8, 118.4, 176.1, 213.1 37 degrees Dry 302.1, 339.2, 288.8, 306.8, 305.2, 327.5 22 degrees Wet 385.3, 368.3, 322.6, 307.4, 357.9, 321.4 37 degrees Wet 363.5, 377.7, 327.7, 331.9, 338.1, 394.6

a. Estimate the difference between the mean breaking force in a dry medium at 37 degrees and the mean breaking force at the same temperature in a wet medium using a 90% confidence interval.

b. Is there sufficient evidence to conclude that the mean breaking force in a dry medium at the higher temperature is greater than the mean breaking force at the lower temperature by more than 100 N? Test the relevant hypotheses using a significance level of .10.