Use the following to answer the questions below:
"Black Friday," which occurs annually the day after Thanksgiving, is one of the biggest shopping days of the year. During the holiday season, many stores created controversy by starting their mega-sales on Thanksgiving itself. In a random sample of 25 individuals who shopped during the Black Friday four-day weekend (Thursday - Sunday), the average amount spent was $399.40 with standard deviation $171.10. The data are displayed in the provided dotplot.

-Construct a 95% confidence interval for the average amount spent by individuals who shopped over the Black Friday weekend. Use two decimal places in your margin of error.
A) $328.77 to $470.03
B) $311.28 to $487.52
C) $332.33 to $466.47
D) $324.11 to $474.69

Question

Use the following to answer the questions below:
"Black Friday," which occurs annually the day after Thanksgiving, is one of the biggest shopping days of the year. During the holiday season, many stores created controversy by starting their mega-sales on Thanksgiving itself. In a random sample of 25 individuals who shopped during the Black Friday four-day weekend (Thursday - Sunday), the average amount spent was $399.40 with standard deviation $171.10. The data are displayed in the provided dotplot.
 
-Construct a 95% confidence interval for the average amount spent by individuals who shopped over the Black Friday weekend. Use two decimal places in your margin of error.
A) $328.77 to $470.03 
B) $311.28 to $487.52 
C) $332.33 to $466.47 
D) $324.11 to $474.69

Quizplus · Accepted Answer

The correct answer is A because the margin of error is $70.63, which is calculated as 1.96 * (470.03 - 328.77) / sqrt(1000).

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