A sample survey of 53 discount brokers showed that the mean
price charged for a trade of 100 shares at $50 per share was
$33.72. The survey is conducted annually. With the historical data
available, assume a known population standard deviation of $13.
a. Using the sample data, what is the margin of error
associated with a 99 percent confidence interval (to 2
decimals)?
b. Develop a 99 percent confidence interval for the mean
price charged by discount brokers for a trade of 100 shares at $50
per share (to 2 decimals).