Question: Groundwater contamination in wells. In New Hampshire, about half the counties mandate the use of reformulated gasoline. This has lead to an increase in the contamination of groundwater with methyl tert-butyl ether (MTBE). Environmental Science and Technology (January 2005) reported on the factors related to MTBE contamination in private and public New Hampshire wells. Data were collected for a sample of 223 wells. These data are saved in the MTBE file. Three of the variables are qualitative in nature: well class (public or private), aquifer (bedrock or unconsolidated), and detectible level of MTBE (below limit or detect). [Note: A detectible level of MTBE occurs if the MTBE value exceeds .2 micrograms per liter.] The data for 10 selected wells are shown in the accompanying table.
(a) Apply a graphical method to all 223 wells to describe the well class distribution.
(b) Apply a graphical method to all 223 wells to describe the aquifer distribution.
(c) Apply a graphical method to all 223 wells to describe the detectible level of MTBE distribution.
(d) Use two bar charts, placed side by side, to compare the proportions of contaminated wells for private and public well classes. What do you infer?
