1)Explain the difference between descriptive and inferential statistics

1)Explain the difference between descriptive and inferential statistics.             

3. Give two reasons the sample mean is the best point estimate for µ.            
4. Define confidence interval and degree of confidence. Make up an example of a confidence               
5. Define margin of error. Explain the relation between the confidence interval and the error estimate. Suppose a confidence interval is 9.65 < µ < 11.35. Find the sample mean x and the error estimate E.

6. Under what circumstances can you replace Η with s in the formula E = z ? /2 · ^Ηn .             

7. How do you determine whether to use the z or t distribution in computing the margin of  , E = z ? /2 · ^Ηn or E = t_?/2 · ^sn ?

distribution is required. Compute the error estimate using either E = z    /2 · ^Ηn or

9. When determining the sample size needed to achieve a particular error estimate you need               .
10. Explain how confidence intervals might be used to make decisions. Give an example to    clarify your explanation.
11. What assumption about the parent population is needed to use the t distribution to compute the margin of error?
12. Under what three conditions is it appropriate to use the t distribution in place of the standard normal distribution?
13. Interpret the following 95% confidence interval for mean weekly salaries of shift managers              at Guiseppe's Pizza and Pasta. 325.80 < µ < 472.30

17. Describe the process for finding the confidence interval for a population proportion.

18. When determining sample size we need to know p^{^}. If we have no prior information, what  are two methods that can be used?
19. When determining the sample size for a desired margin of error, the formula is

z               ^/2 2 · p^{^} q^{^}   . Based on this formula, discuss the fact that sample size is not n =               ^?

E2 dependent on the population size; that is, it is not necessary to sample a particular percent of the population.

20. Why would manufacturers and businesses be interested in constructing a confidence interval for the population variance? Would manufacturers and businesses want large or small variances?
21. Draw a diagram of the chi- square distribution. Discuss its shape and values.      

22. A radio show host asked people to call in and say whether they support new legislation to  promote cleaner sources of energy.  Based on this sample, she constructed a confidence interval to estimate the proportion of all listeners to her show who support the legislation. Is the confidence interval likely to give a good estimate of the proportion of her listeners who support the legislation?

23. Bert constructed a confidence interval to estimate the mean weight of students in his class.             

The population was very small - only 30. Ruth constructed a confidence interval for the mean weight of all adult males in the city.  She based her confidence interval on a very small sample of only 5. Which confidence interval is likely to give a better estimate of the mean it is estimating? Which is likely to be more of a problem, a small sample or a small population?

24. A paper published the results of a poll. It stated that, based on a sample of 1000 married  men, 51% of married men say that they would marry the same woman again.  The margin of error was given as ±3  percentage points and the confidence level was given as 95%. What does it mean that the margin of error was ±3  percentage points?
25. Mark wanted to estimate the mean number of years of education of adults in his city. He  waited outside a public library and interviewed every tenth adult leaving.  Based on this sample, he constructed a confidence interval for the mean number of years of education of adults in the city. Do you think this confidence interval will give a good estimate? Why or why not?
26. Based on a simple random sample of students from her school, Sally obtained a point       estimate of the mean weight of students at her school. What additional information would be provided by a confidence interval estimate of the mean weight?
27. Hannah selected a simple random sample of all adults in her town and, based on this      sample,  constructed a confidence interval for the mean salary of all adults in the town. However, the distribution of salaries in the town is not exactly normal. Will the confidence interval still give a good estimate of the mean salary?