The average cost per night for a hotel room in New York City is $ 273 (Smart Money, March 2009). Assume that this estimate is based on a sample of 45 hotels and that the sample standard deviation is $ 65. a) With 95% confidence, what is the margin of error? b) What is the 95% confidence interval estimate for the population mean? c) Two years ago, the average cost per night for a hotel room in New York was $ 229. Analyze the variation in cost in this two-year period