A National Retail Foundation survey found households intended to spend an average of $649 during the December holiday season (The Wall Street...

A National Retail Foundation survey found households intended to spend an average of $649 during the December holiday season (The Wall Street Journal, December 2, 2005). Assume that the survey included 600 households and that the sample standard deviation was $175. a. With 99% confidence, determine the margin of error.b. Determine the 99% confidence interval estimate of the population mean