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Chapter 8: Q 8.53 (page 331)
State True or False. Give Reasons for your answers.
The length of the confidence interval can be determined if you know only the margin of error.
The given statement is True.
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Northeast Commutes. Refer to Exercise
a. Determine and interpret a upper confidence bound for the mean commute time of all commuters in Washington, DC.
b. Compare your one-sided confidence interval in part (a) to the (twosided) confidence interval found in Exercise
A simple random sample is taken from a population and yields the following data for a variable of the population:
find a point estimate for the population standard deviation (i.e., the standard deviation of the variable).
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.
Keep on Rolling. The Rolling Stones, a rock group formed in the , have toured extensively in support of new albums, Pollstar has collected data on the earnings from the Stones's North American tours. For thirty randomly selected Rolling Stones concerts, the mean gross earnings is million. Assuming a population standard deviation gross earnings of million, obtain a confidence interval for the mean gross earnings of all Rolling Stones concerts. Interpret your answer in words.
A simple random sample is taken from a population and yields the following data for a variable of the population:
Find a point estimate for the population mean (i.e., the mean of the variable).
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