Low Blood Lead Level: High Blood Lead Level: n = 78, x = 92.88462, s = 15.34451 n = 21, 3 = 86.90476, s = 8.988352
In Exercises 5–20, assume that the two samples are independent simple random samples selected from normally distributed populations, and do not assume that the population standard deviations are equal. (Note: Answers in Appendix D include technology answers based on Formula 9-1 along with “Table” answers based on Table A-3 with df equal to the smaller of n1 − 1 and n2 − 1.)
IQ and Lead 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 the hypothesis test in part (a).
c. Does exposure to lead appear to have an effect on IQ scores?
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