Assume that a sample is used to estimate a population mean M. Find the 99.9% confidence interval for a sample of size 71 with a mean of 67.5 and a standard deviation of 20.8. Enter your answer as an open- interval (i.e., parentheses) accurate to one decimal place (because the sample statistics are reported accurate to one decimal place). 99.9% C. I. = Answer should be obtained without any preliminary rounding. However, the critical value may be rounded to 3 decimal places