In Exercises 5–20, assume that the two samples are independent simple random samples selected from
12. IQ and Load Exposure Data Set 7 “IQ and Lead” in Appendix B lists full IQ scores for a random sample of subjects with low lead levels in their blood and another random sample of subjects with high lead levels in their blood. The statistics are summarized below.
a. Use a 0.05 significance level to test the claim that the
b. Construct a confidence interval appropriate for tire hypothesis test in part (a).
c. Does exposure to lead appear to have an effect on IQ scores?
Low Blood Lead Level: n = 78,
High Blood Lead Level: n = 21,
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