Ajournalist wants to determine the average annual salary of ceos in the s& p 1,500. he does not have time to survey all 1,500 ceos but wants to be 95% confident that his estimate is within $50,000 of the true mean. the journalist takes a preliminary sample and estimates that the standard deviation is approximately $449,300. what is the minimum number of ceos that the journalist must survey to be within $50,000 of the true average annual salary? remember that the z-value associated with a 95% confidence interval is 1.96.