Refer to the Environmental Science & Technology (Jan. 2005) study of methyl tert-butyl ether (MTBE) contamination in 223 New Hampshire wells, Exercise 3.7. Each well is classified according to well class (public or private), aquifer (bedrock or unconsolidated), and detectable level of MTBE (below limit or detect). Consider one of these 223 wells.
a. What is the probability that the well has a bedrock aquifer and a detected level of MTBE?
b. What is the probability that the well has a bedrock aquifer or a detected level of MTBE?

Data from Exercise 3.7

Data collected for a sample of 223 wells are saved in the MTBE file. Recall that each well was classified according to well class (public or private), aquifer (bedrock or unconsolidated), and detectable level of MTBE (below limit or detect).