Travel and Transportation
The U.S. Department of Transportation requires vehicles transporting hazardous materials to use special placards indicating the type of cargo. There are many other regulations involving containers, separation of various materials, and gross weight. Independent random samples of trucks carrying corrosive materials were stopped on highways in North Carolina and in Virginia, and the weight (in kg) of the hazardous material was recorded. The summary statistics and known variances are given in the following table.
Is there any evidence to suggest that the mean amount of corrosive material carried by trucks in North Carolina is different from the mean amount of corrosive material carried by trucks in Virginia? Use a = 0.01 and assume each underlying distribution of weight is normal.