Exercise 2.51 on page 71 discusses the use of toenail clippings to measure the level of arsenic exposure of individuals in Great Britain. A similar study was conducted in the US. Table 2.23 gives toenail arsenic concentrations (in ppm) for 19 individuals with private wells in New Hampshire, and the data are also available in ToenailArsenic. Such concentrations prove to be an effective indicator of ingestion of arsenic-containing water.

Table 2.23

(a) Use technology to find the mean and standard deviation.
(b) Compute the z-score for the largest concentration and interpret it.

(c) Use technology to find the five number summary.
(d) What is the range? What is the IQR?

Exercise 2.51

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