Question 322483
<pre><b>
On your TI-83 or TI-84

Press ON
Press CLEAR
Press 2ND
Press 0  (zero)
Press x<sup>-1</sup>
Press down arrow 9 times to scroll to DiagnosticOn
Press ENTER  (read DiagnosticOn
Press ENTER  (read Done

Press CLEAR
Press STAT
Press 1
(enter the data for the number of absences in L1
(enter the data for the final grades in L2

Press 2ND
Press Y=
Press ENTER
Press ENTER (again)

Press STAT
Press right arrow >
Press 4    
(you'll see LinRed(ax+b)

Press VARS
Press right arrow >
Press ENTER
Press ENTER again

See this:
LinReg
 y=ax+b
 a=-8.873076923
 b=95.3
 rē=.9149096479
 r=-.9565090945 

That means the regression line is y = -8.873076923x + 95.3
and the correlation coefficient is  r=.9565090945

To see the scatter plot and the regression line:

Press ZOOM
Press 9 

Edwin</pre>