You intend to estimate a population mean / with the following sample. 76.3 43.1 43.6 19.3 9.8 55.2 30.1 -13.3 -8.1 34.2 18.8 17.9 You believe the population is normally distributed. Find the 80% confidence interval. Enter your answer as an open-interval (i.e., parentheses) accurate to two decimal places (because the sample data are reported accurate to one decimal place). 80% C.I. = Answer should be obtained without any preliminary rounding. However, the critical value may be rounded to 3 decimal places