The average cost per night of a hotel room in New York City is $273 (SmartMoney, March 2009).Assume 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 of the population mean? c. Two years ago the average cost of a hotel room in New York City was $229. Discuss the change in cost over the two-year period.