In a poll of 1009 U.S. adults of age 18 years and older, conducted December 4–7, 2008, Gallup asked “Roughly how much money do you think you personally will spend on Christmas gifts this year?”. The data provided on the WeissStats CD are based on the results of the poll.
a. Determine a 95% upper confidence bound for the mean amount spent on Christmas gifts in 2008. (Note: The sample mean and sample standard deviation of the data are $639.00 and $477.98, respectively.)
b. Interpret your result in part (a).
c. In 2007, the mean amount spent on Christmas gifts was $833. Comment on this information in view of your answer to part (b).

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