Refer to the University of Alaska study to monitor the level of radioactivity in lichen, Exercise 2.15. The amount of the radioactive element cesium-137 (measured in microcuries per milliliter) for each of nine lichen specimens is repeated in the table.

a. Find the mean, median, and mode of the radioactivity levels.

b. Interpret the value of each measure of central tendency, part a.

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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Location Bethel -5.50 -5.000 Eagle Summit -4.15 -4.85 Moose Pass -6.05 Turnagain Pass -5.00 Wickersham Dome -4.10 -4.50 -4.60