17. The article The Lead Content and Acidity of Christchurch Precipitation (New Zeal. J. Sci., 1980:

311—312) reports the accompanying data on lead concentration (mg/L) in samples gathered during eight differentsummerrainfalls: 17.0, 21.4, 30.6, 5.0, 12.2, 11.8, 17.3, and 18.8. Assuming that the leadcontent distribution is symmetric, use theWilcoxon signed-rank interval to obtain a 95% CI for m.