For the first six months of the year, an analyst records the monthly closing stock price (in $) for a firm as: 240, 245, 249, 248, 246, 242.

a. Calculate the sample mean and the sample standard deviation. (Round final answer to 2 decimal places.)

b. Calculate the 99% confidence interval for the mean stock price of the firm assuming that the stock price is normally distributed. (Round final answer to 2 decimal places.)

c. What happens to the margin of error if a higher confidence level is used for the interval estimate? multiple choice The margin of error decreases as the confidence level increases. The margin of error increases as the confidence level increases.