- Press STAT.
- Press the right arrow key to scroll over to the TESTS menu.
- Press the down arrow key to scroll down until 2-PropZInt is highlighted.
- Press ENTER.
- Input the number of “successes” for the first group next to the x1 (remember: this must be a whole number).
- Input the sample size for the first group next to the n1.
- Input the number of “successes” for the second group next to the x2.
- Input the sample size for the second group next to the n2.
- Input the desired 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