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On your TI-83 or TI-84
Press ON
Press CLEAR
Press 2ND
Press 0 (zero)
Press x-1
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