Refer to the Lichen Radionuclide Baseline Research project, Exercise 2.15. University of Alaska researchers determined the amount of the radioactive element cesium-137 for nine lichen specimens sampled from various Alaskan locations. The data values (measured in microcuries per milliliter) are given in the table.

a. Describe the population of interest to the researchers.
b. Estimate the mean of the population using a 95% confidence interval.
c. Make an inference about the magnitude of the population mean.
d. For the inference to be valid, how must the population data be distributed?

Data from Exercise 2.15

Lichen has a high absorbance capacity for radiation fallout from nuclear accidents. Since lichen is a major food source for Alaskan caribou, and caribou are, in turn, a major food source for many Alaskan villagers, it is important to monitor the level of radioactivity in lichen. Researchers at the University of Alaska, Fairbanks, collected data on nine lichen specimens at various locations for this purpose. The amount of the radioactive element, cesium- 137, was measured (in microcuries per milliliter) for each specimen. The data values, converted to logarithms, are given in the table. (Note, the closer the value is to zero, the greater the amount of cesium in the specimen.)

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LICHEN 0.0040868 0.0157644 0.0023579 0.0067379 0.0165727 0.0067379 0.0078284 0.0111090 0.0100518