Lead exposure can cause many neurological problems in young children. Lead exposure is measured as the lead blood level in micrograms per 100 mL. A study in Los Angeles, California, wanted to determine if lead blood levels were higher in children who lived less than 2 miles from a factory as compared to children who lived at least two miles away from a factory.

• A. One-tail t-test
• B. Chi-squared test
• C. One-tail z-test
• D. Two-tail t-test
• E. Correlation
• F. Two-tail z-test