In May 2007, a banker was arrested and charged with insider trading after government investigators had secretly looked at a sample of nine of his many trades and found that on these trades he had made a total of $7.5 million. Compute the average earning per trade. Assume also that the sample standard deviation was $0.5 million and compute a 95% confidence interval for the average earning per trade for all trades made by this banker. Use the assumption that the nine trades were randomly selected.