Week 5 Assignment
1. Explain why it is important to calculate a confidence interval when we do not have data from the entire population. Why can?t we just use a sample mean?
2. Explain the meaning of the term ?93% confidence? in the following scenario without using the word ?confident? or ?confidence? (or synonyms like certain, sure?) in the part you must add.
Scenario: You are measuring the length of fish in a pond and want to know the mean length of the population of fish. You must begin your explanation with ?Assume I have data from 100 samples of fish taken from the pond. The 93% confidence interval indicates that?.?
3. For a fixed level of confidence, what happens to a confidence interval for ? when we increase the sample size?
4. Suppose that for a sample size of n=57, we find that the sample mean is 611. Assuming that the standard deviation = 14, calculate the confidence intervals for the population mean ? with the following confidence levels.
a. 90%
b. 92%
c. 95%
d. 97%
e. 99%
5. Compare the shape of the t curve to the shape of the z curve. What are their similarities and differences?
6. Locate a flowchart online which helps you determine when to use t and when to use z in your calculations. The flow chart should include knowledge of population standard deviation and sample size. Cite your source.
