Chapter 8: Q 8.54 (page 331)
State True or False. Give Reasons for your answers.
The margin of error can be determined if you know only the length of the confidence interval.
The statement is True.
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Medical Marijuana. Refer to Exercise 8.77.
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?
Shoe and Apparel E-Tailers. In the special report "Mousetrap: The Most-Visited Shoe and Apparel E-tailers" (Foonucar News, Vol. 58 . No. 3. p. 18), we found the following data on the average time, in minutes, spent per user per month from January to June of one year for a sample of shoe and apparel retail websites.
Explain the effect on the margin of error and hence the effect on the accuracy of estimating a population mean by a sample mean.
Decreasing the sample size while keeping the same confidence level.
Assume that the population standard deviation is known and decide weather use of the z-interval procedure to obtain a confidence interval for the population mean is reasonable. Explain your answers .
The sample data contain no outliers, the sample size is , and the variable under consideration is far from being normally distributed.
A confidence interval for a population mean has a margin of error of
a. Determine the length of the confidence interval.
b. If the sample mean is , obtain the confidence interval.
c. Construct a graph that illustrates your results.
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