A sample survey of 30 discount brokers showed that the mean price charged for a trade of 100shares at $50 per share was $40 and a sample standard deviation was $10. (a) Using the sample data, what is the margin of error associated with a 99% confidence interval? (b) Develop a 95% confidence interval for the mean price charged by discount brokers for a trade of 100 shares at $50 per share. (c) Write a summary based on your findings of (b).