- Press STAT.
- Press the right arrow key to scroll over to the TESTS menu.
- Press the down arrow key to scroll down until ZInterval or TInterval is highlighted (whichever is appropriate).
- Press ENTER.
- Specify whether you are using raw data, or stats (if you are using raw data, you need to enter that data into one of the lists before attempting to create the interval).
- If you’re using raw data, input the location of the data, the frequency of the data points contained in the list (usually 1), and the confidence level, formatted as a decimal.
- If you’re using stats, enter the sample mean, the population or sample standard deviation (whichever is appropriate), the sample size, and the confidence level, formatted as a decimal.
- Highlight the word Calculate and press ENTER.
- The calculator should now display the desired confidence interval.
Old Operating System Manual