Christmas Spending. In a national poll of 1039 U.S. adults, conducted November 7–10, 2013, Gallup asked “Roughly how much money do you think you personally will spend on Christmas gifts this year?”. The data provided on the WeissStats site are based on the results of the poll.

a. Determine a 95% upper confidence bound for the mean amount spent on Christmas gifts in 2013. (Note: The sample mean and sample standard deviation of the data are $704.00 and $477.98, respectively.)

b. Interpret your result in part (a).

c. In 2012, the mean amount spent on Christmas gifts was $770.

Comment on this information in view of your answer to part (b).