(Tested on a Texas Instrument TI-84 Plus)
1.) Press STAT and choose 1: EDIT.
2.) If there are numbers listed you will needed to clear the numbers. If it is already clear then go on to the next step. To clear the numbers:
Make sure L1 is highlighted, then press CLEAR, then press DOWN ARROW.
To clear the next column hit the ARROW BUTTONS until L2 is highlighted, then press CLEAR, the press DOWN ARROW.
3.) Now enter the data numbers into List 1 (L1) by pressing each number followed by the ENTER button.
Hit the RIGHT ARROW to enter the L2 column and begin entering the data numbers into List 2.
4.) Next select STAT PLOT by pressing 2ND then Y=.
5.) Select 1: Plot1 by pressing 1.
6.) Make sure of the following:
Plot1 is highlighted
ON is highlighted
The first graph after Type: is highlighted
The square after Mark: is highlighted.
Your screen should match the image to the right.
7.) Press ZOOM, then 9. You will now see a graph.
8.) Now press STAT, then RIGHT ARROW to highlight CALC, then press 4 to select 4:LinReg(ax+b)
9.) Your screen should now say:
Now press 2ND, then 1 to output L1.
Then press the COMMA BUTTON, then press 2ND , then press 2 to output L2.
Then press the COMMA BUTTON, then press VARS, then press RIGHT ARROW to highlight
Y-VARS, the press 1 to select FUNCTION, the press 1 to select 1:Y1.
10.) Your screen should now say:
LinReg(ax+b) L1, L2, Y1
Now press ENTER.
11.) Your screen should now say:
Write down the number after ‘a=’. That is your slope. You can round it to the second decimal place.
Write down the number after ‘b=’. That is your y-intercept. You can round it to the second decimal place.
Plug these numbers into slope-intercept form to get your equation of the line (y=mx +b).
12.) Now press ZOOM, then press 9.
You graph should appear with the Line of Best Fit drawn.
Copy the graph down as close as possible. It does not have to be exact.