Salmonella in produce. Salmonella is the most common type of bacterial food-borne illness in the United States. How prevalent is salmonella in produce grown in the major agricultural region of Monterey, California?

Researchers from the United States Department of Agriculture (USDA) conducted tests for salmonella in produce grown in the region and published their results in Applied and Environmental Microbiology (Apr. 2011).

In a sample of 252 cultures obtained from water used to irrigate the region, 18 tested positive for salmonella. In an independent sample of 476 cultures obtained from the region’s wildlife (e.g., birds), 20 tested positive for salmonella.

Is this sufficient evidence for the USDA to state that the prevalence of salmonella in the region’s water differs from the prevalence of salmonella in the region’s wildlife?

Use a = .01 to make your decision.