The newer TI-84 calculators are a little different from the older ones.
The first and last part is the same on all of them. I'll let you know
when they differ:
On your TI-84,
Press CLEAR
Press Y=
clear anything that's there
Press the up arrow to highlight Plot1
Press ENTER
Press STAT
Press 1
Enter the X values in L1
Enter the Y values in L2
Press STAT
Press the right arrow
Press 4
Now here is where they differ.
On the older versions you will see: | On the newer versions you will see:
|
LinReg(ax+b) ∎ | LinReg(ax+b)
Press VARS | Xlist:L1
Press the right arrow | Ylist:L2
Press 1 | FreqList:
Press 1 | Store RegEQ:
| Calculate
You should see |
| Press the down arrow 3 times to
LinReg(ax+b) Y1 | get cursor beside Store RegEQ:∎
| Press ALPHA
| Press TRACE
Press ENTER | Press ENTER (puts Y1 after the colon)
| Press ENTER
| Press ENTER
-----------------------------------------------------------------------------
You will see:
y=ax+b
a=2.096969697
b=-.5515151515
r²=.9794161922
r=.9896545822
So the equation of the regression
line is
y = 2.096969697x - .5515151515
Press ZOOM
Press 9
You will see the regression line graphed
To predict the value when X = -2
Press 2nd
Press TRACE
Press 1
The graph comes back with X=∎
Press -2 [Use the negative sign (-) not the minus sign —]
Press ENTER
Read at bottom of screen: X=-2 Y=-4.745455
To predict the value when X = 4
Press 4
Read at bottom of screen: X=4 Y=7.8363636
Edwin