Steps | Key Sequence | Screens |
1. Set up Stats Tests | STAT | |
twice | ||
7 (for ZInterval...) | ||
2. Select Input | once then ENTER | |
3. Input standard deviation | once, enter standard devation of POPULATION (if known, otherwise use standard devation of sample), then ENTER | |
4. Input mean of SAMPLE | enter mean of SAMPLE, then ENTER | |
5. Input sample size | enter sample size, then ENTER | |
6. Input confidence level | enter confidence level (AS DECIMAL), then ENTER | |
7. Calculate CI | ENTER | |
In this case the 90% CI is 3.0101 to 3.3899. |