Probability & Statistics Finding the Confidence Interval

Question

You must estimate the mean temperature (in degrees Fahrenheit) with the following sample temperatures:

69
74.8
68.5
59.4
92.7
82.2
74.7
56.7
71.8
73.3
69.6

Find the 99% 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).

99% C.I. = 

Answer should be obtained without any preliminary rounding.

Answer 1

Find the mean and the sample standard deviation for this data on a TI-84

For a 99% CI the Z value is 2.58

Then the CI is mean +- 2.58 x standard deviation / sqrt (11), as there are 11 data points

I got mean = 72.06, standard deviation ia 9.84, giving CI = [64.41, 79.71]