A sample survey of 57 discount brokers showed that the mean price charged for a trade of 100 shares at $50 per share was $33.86. The survey is conducted annually. With the historical data available,...

Extracted text: A sample survey of 57 discount brokers showed that the mean price charged for a trade of 100 shares at $50 per share was $33.86. The survey is conducted annually. With the historical data available, assume a known population st deviation of $13. a. Using the sample data, what is the margin of error associated with a 95% confidence interval (to 2 decimals)? b. Develop a 95% confidence interval for the mean price charged by discount brokers for a trade of 100 shares at $50 per share (to 2 decimals).