- Input the data into two lists (one list for the x-values and one for the y-values).
- Press STAT.
- Press the right arrow key to scroll over to the TESTS submenu.
- Press the down arrow key to scroll down until LinRegTInt is highlighted and press ENTER.
- Select your x list and y list (the two lists where your data are stored).
- Select the frequency (usually 1).
- Input your 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