(5 points) Choose a population and a quantitative variable which is
approximately normally distributed within this population. Clearly
state your choices in a few sentences.
2. (20 points) Justify why your variable is normally distributed within its
population in a few sentences.
3. (15 points) Guess a value for the population standard deviation σ.
Justify your guess in a few sentences.
4. (20 points) Collect a simple random sample of 20−30 individuals from
your population. Give a detailed description of your sampling method
and justify why it is a simple random sampling method in one to two
paragraphs.
5. (30 points) Compute z-confidence intervals using your sample data,
guess of σ, and confidence levels of 90%, 95%, and 99%. Your work
should include the value of Ì„x, your z
∗
-value for each confidence level,
and the actual intervals themselves.
6. (10 points) Explain what these three confidence intervals together tell
you about the value of the population mean μ. Justify your answer in
one to two paragraphs.