Americium 241 (241Am) is a radioactive material used in the manufacture of smoke detectors. The article "Retention and Dosimetry of Injected 241Am in Beagles" (Radiation Research [1984]: 564-575) described a study in which 55 beagles were injected with a dose of 241Am (proportional to each animal's weight). Skeletal retention of 241Am (in microcuries per kilogram) was recorded for each beagle, resulting in the following data:
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a. Construct a frequency distribution for these data, and draw the corresponding histogram.
b. Write a short description of the important features of the shape of the histogram.