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Chapter 8: Q 8.31 (page 330)
For what is normal population an abbreviation?
It mean variables are normally distributed.
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American Alligators. Refer to Exercise 8.78.
a. Determine the margin of error for the confidence interval.
b. Determine the margin of error for the confidence interval.
c. Compare the margins of error found in parts (a) and (b).
d. What principle is being illustrated?
Bicycle Commuting Times. A city planner working on bikeways designs a questionnaire to obtain information about local bicycle commuters. One of the questions asks how long it takes the rider to pedal from home to his or her destination. A sample of local bicycle commuters yields the following times, in minutes. 
a. Find a confidence interval for the mean commuting time of all local bicycle commuters in the city. (Note: The sample mean and sample standard deviation of the data are minutes and minutes, respectively.)
b. Interpret your result in part (a).
c. Graphical analyses of the data indicate that the time of utes may be an outlier. Remove this potential outlier and repeat part (a). (Note: The sample mean and sample standard deviation of the abridged data are and , respectively.)
d. Should you have used the procedure that you did in part (a)? Explain your answer.
Must the variable under consideration be normally distributed for you to use the z-interval procedure or interval procedure? Explain your answer.
Table IV in Appendix A contains degrees of freedom from to consecutively but then contains only selected degrees of freedom.
a. Why couldn't we provide entries for all possible degrees of freedom?
b. Why did we construct the table so that consecutive entries appear for smaller degrees of freedom but that only selected entries occur for larger degrees of freedom?
c. If you had only Table IV, what value would you use for os with df with with with ? Explain your answers.
The margin of error is also called the maximum error of the estimate. Explain why.
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