Arsenic is toxic to humans, and people can be exposed to it through contaminated drinking water, food, dust, and soil. Exercises 2.51 and 2.103 on pages 71 and 87, respectively, describe an interesting new way to measure a person€™s level of arsenic poisoning: by examining toenail clippings. Two samples of arsenic in toenails are given below: one from near an arsenic mine in Great Britain and one from New Hampshire, US. In each case, find a 95% confidence interval for the level of arsenic in toenails in the relevant population. First, determine whether it appears to be appropriate to use a t-distribution to construct the confidence interval. If a t-distribution is appropriate, use it. If not, use a bootstrap method. Note that the units for measuring arsenic (mg/kg or ppm) are not the same for the two studies.
(a) Levels of arsenic, measured in mg/kg, are given below for 8 people living near a former arsenic mine in Great Britain:

(b) Levels of arsenic, measured in ppm, are given for 19 individuals with private wells in New Hampshire in Table C.6 (and stored in ToenailArsenic).

Table C.6

Exercises 2.51 and 2.103 on pages 71 and 87

Arsenic is toxic to humans, and people can be exposed to it through contaminated drinking water, food, dust, and soil. Scientists have devised an interesting new way to measure a person€™s level of arsenic poisoning: by examining toenail clippings. In a recent study,29 scientists measured the level of arsenic (in mg/kg) in toenail clippings of eight people who lived near a former arsenic mine in Great Britain. The following levels were recorded:

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0.8 1.9 2.7 3.4 3.9 7.1 11.9 26.0 0.119 0.118 0.099 0.118 0.275 0.358 0.080 0.158 0.310 0.105 0.269 0.433 0.141 0.073 0.832 0.517 0.851 0.135 0.175