Use the following sample to estimate a population mean . 85 75.9 94.7 72.3 75.3 87.9 72.2 80.7 95.9 76 Assuming the population is normally distributed, find the 80% confidence interval about the populat mean. Enter your answer as an open-interval (i.e., parentheses) accurate to two decimal places. 80% C.I.=