TIp 7: Creating a Statistical Plot
Fundamental Topics in Science © 2001 Texas Instruments
TIp 7-4
Try-It!
Ë
on Your TI
83 Plus
(continued)
On Your Own
1. Enter the following math test scores in
L
1
and
L
2
.
Scores (L
1
) Frequency (L
2
)
99 4
96 4
92 3
88 2
84 3
78 2
74 2
70 1
66 1
64 1
2. Set up the histogram (
Ò
) where
Xlist=L
1
and
Freq=L
2
in the
STAT PLOTS
menu.
3. Graph the histogram using
ZoomStat
, and then trace (
)
) the histogram. Letter grades
correspond to these test scores: A = 100–90; B = 89–80; C = 79–70; D = 69–60; F = 59–0. Did
the graph display the way you expected? Why is it necessary to change the window values
manually?
4. Change the window values manually to group the data in intervals of 10. Remember that you
want the data grouped in intervals of 10 so you can see how many test scores fall into the
grade categories given above. You can tell the calculator to do this by setting
Xscl=10
on the
graphing window (
'
).
Xmin
should be a little less than the lowest score and
Xmax
should be a little higher than the highest score to display a nice graph. Try setting the
window as
Xmin=50
,
Xmax=100
,
Ymin=
0
0
4
,
Ymax=15
, and
Yscl=10
.
5. Graph and trace the histogram again to see why these settings show the grades grouped by
scores that match the letter grades A, B, C, D, and F.
Hint
: Remember that if you have functions defined and turned on in the Y= editor, the calculator graphs these at the same time as the
stat plot. To turn off a function, highlight the = sign next to it, and then press
b
.
You can also select
FnOff
to turn off all functions. To do this, press
r
a
4:On/Off
2:FnOff
.
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