Consider the accompanying data on breaking load (kg/25 mm width) for various fabrics in both an unabraded condition and an abraded condition (“The Effect of Wet Abrasive Wear on the Tensile Properties of Cotton and Polyester-Cotton Fabrics,” J. Testing and Evaluation, 1993: 84–93). Use the paired t test, as did the authors of the cited article, to test versus at significance level .01.

Ha H0: mD 5 0 : mD . 0 12345678 U 36.4 55.0 51.5 38.7 43.2 48.8 25.6 49.8 A 28.5 20.0 46.0 34.5 36.5 52.5 26.5 46.5