Assume that a sample is used to estimate a population mean Find the 99.9% confidence interval for a sample of size 69 with a mean of 55.6 and a standard deviation of 13.1. Enter your answer as anopen-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.