Assume that a sample is used to estimate a population mean

Find the 80% confidence interval for a sample of size 59 with a mean of 69.1 and a standard deviation of 21.5. 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).

80% C.I. =

Answer should be obtained without any preliminary rounding. However, the critical value may be rounded to 3 decimal places.