Chapter 13: Inferential Statistics and Distributions
217
If the height distribution among a population of women is normally distributed with a mean
m
of
165.1 centimeters and a standard deviation
s
of 6.35 centimeters, what height is exceeded by only
5 percent of the women (the 95th percentile)?
The result is displayed on the home screen; it shows that five percent of the women are taller than
175.5 centimeters.
Now graph and shade the top 5 percent of the population.
2. Press
†
163
Ë
8
Í
to store 163.8 to
v
.
Press
7
Ë
1
Í
to store 7.1 to
Sx
.
Press
90
Í
to store 90 to
n
.
3. 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.
4. Press
‘
to clear the home screen.
Press
y =
to display the
DISTR
(distributions) menu.
5. Press
3
to open the
invNorm(
wizard. Enter the
information as follows:
Press
Ë
95
†
165
Ë
1
†
6
Ë
35
†
(95 is the
area, 165.1 is
m
, and 6.35 is
s
).
6. Press
Í
to paste the function and
Í
again
to calculate the result.
7. Press
p
and set the window variables to
these values.
Xmin=145 Ymin=
L
.02 Xres=1
Xmax=185 Ymax=.08
Xscl=5 Yscl=0