TI-83 Instructions

Confidence Intervals for the Mean using a Large Sample

Method 1 - Data

1. Enter the sample data into a list, say L1.
2. If the standard deviation of the population is unknown, then find the standard deviation of the sample. Record this number.
3. Press STAT. The STAT menus appear and the EDIT menu title is highlighted.
4. Select the TESTS menu title. The TESTS menu appears.
5. Select ZInterval, item #7. A list of options appears.
6. On the first line are two options: Data and Stats. Use the arrow keys to select Data.
7. Press ENTER.
8. Press the down arrow once.
9. Enter the standard deviation of the population, if it is known. Otherwise, enter the standard deviation of the sample.
10. Press the down arrow once.
11. Enter the name of the list (L1) that contains the data.
12. Press the down arrow twice, skipping over the Freq option.
13. Enter the confidence level as a decimal, not a percent.
14. Press the down arrow once. The word Calculate begins to flash.
15. Press ENTER. The confidence interval appears, in interval notation, along with the sample mean, sample standard deviation, and sample size.

Method 2 - Statistics

1. Follow Steps 3 − 5 in Method 1 above.
2. Use the arrow keys to select the Stats option.
3. Press ENTER.
4. Press the down arrow once.
5. Enter the standard deviation of the population, if it is known. Otherwise, enter the standard deviation of the sample.
6. Press the down arrow once.
7. Enter the mean of the sample.
8. Press the down arrow once.
9. Enter the sample size.
10. Press the down arrow once.
11. Follow Steps 13 − 15 in Method 1 above. The confidence will appear along with the sample mean and the sample size.