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13-4 Inferential Statistics and Distributions
8313INFE.DOC TI-83 international English Bob Fedorisko Revised: 02/19/01 12:47 PM Printed: 02/19/01 1:38 PM
Page 4 of 36
To obtain a more precise bound on the population mean
m
of women’s heights,
increase the sample size to 90. Use a sample mean
þ
of 163.8 and sample
standard deviation
Sx of 7.1 calculated from the larger random sample
(introduction; page 13
.
2). This time, use the
Stats (summary statistics) input
option.
7. Press
…
|
8 to display the inferential
stat editor for
TInterval.
Press
~
Í
to select
Inpt:Stats. The
editor changes so that you can enter
summary statistics as input.
8. Press
†
163
Ë
8
Í
to store 163.8 to
þ
.
Press
7
Ë
1
Í
to store 7.1 to Sx.
Press
90
Í
to store 90 to n.
9. Press
†
to move the cursor onto Calculate,
and then press
Í
to calculate the new
99 percent confidence interval. The results
are displayed on the home screen.
If the height distribution among a population of women is normally distributed
with a mean
m
of 165.1 cm. and a standard deviation
σ
of 6.35 cm., what height
is exceeded by only 5 percent of the women (the 95th percentile)?
10. Press
‘
to clear the home screen.
Press
y
[
DISTR
] to display the
DISTR
(distributions) menu.