A preliminary study was conducted to obtain information on the background levels of the toxic substance polychlorinated

Question:

A preliminary study was conducted to obtain information on the background levels of the toxic substance polychlorinated biphenyl (PCB) in soil samples in the United Kingdom (Chemosphere, Feb. 1986). Such information could then be used as a benchmark against which PCB levels at waste disposal facilities in the United Kingdom can be compared. The accompanying table contains the measured PCB levels of soil samples taken at 14 rural and 15 urban locations in the United Kingdom (PCB concentration is measured in .0001 gram per kilogram of soil). From these preliminary results, the researchers reported “a significant difference between (the PCB levels) for rural areas . . . and for urban areas.” Do the data support the researchers’ conclusions? Test using α = .05.