Question 639646
I. What is the population?


The set of all 50 year old adults.

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II. What is the sample?


The 100 people randomly selected (from the population) for this study

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III. Is the study observational or experimental? Justify your answer.


It's an observation because the researchers are simply looking at data and they are NOT manipulating the subjects in any way. They are also NOT splitting the subjects into two groups (the control and experimental group.

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IV. What are the variables?


The variables are cholesterol  level and hostility level.

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V. For each of those variables, what level of measurement (nominal, ordinal, interval, or ratio) was used to obtain data from these variables?


Cholesterol Level: Ratio (since they can be ordered, the differences make sense, and there's a 0)


Hostility Level: Ordinal (assuming you have something like "not hostile", "somewhat hostile" and "very hostile")