The accompanying data was obtained in a study to evaluate the liquefaction potential at a proposed nuclear power station

(“Cyclic Strengths Compared for Two Sampling Techniques,”
J. of the Geotechnical Division, Am. Soc. Civil Engrs.
Proceedings, 1981: 563–576). Before cyclic strength testing, soil samples were gathered using both a pitcher tube method and a block method, resulting in the following observed values of dry density (lb/ft3 ):
Pitcher sampling 101.1 111.1 107.6 98.1 99.5 98.7 103.3 108.9 109.1 104.1 110.0 98.4 105.1 104.5 105.7 103.3 100.3 102.6 101.7 105.4 99.6 103.3 102.1 104.3 Block sampling 107.1 105.0 98.0 97.9 103.3 104.6 100.1 98.2 97.9 103.2 96.9 Calculate and interpret a 95% CI for the difference between true average dry densities for the two sampling methods.