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13-30 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 30 of 36
normalcdf( computes the normal distribution probability
between
lowerbound
and
upperbound
for the specified
mean
m
and standard deviation
s
. The defaults are
m
=0
and
s
=1.
normalcdf(
lowerbound
,
upperbound
[
,
m
,
s
])
invNorm( computes the inverse cumulative normal
distribution function for a given
area
under the normal
distribution curve specified by mean
m
and standard
deviation
s
. It calculates the
x
value associated with an
area
to the left of the
x
value. 0
area
1 must be true.
The defaults are
m
=0 and
s
=1.
invNorm(
area
[
,
m
,
s
])
tpdf( computes the probability density function (pdf) for
the Student-
t
distribution at a specified
x
value.
df
(degrees
of freedom) must be >0. To plot the Student-
t
distribution,
paste
tpdf( to the
Y=
editor. The probability density
function (pdf) is:
fx
df
df
xdf
df
df
()
[( ) ]
()
()
()
=
++
−+
Γ
Γ
12
2
1
2
12
/
/
/
/
π
tpdf(
x
,
df
)
Note:
For this example,
Xmin =
L
4.5
Xmax = 4.5
Ymin = 0
Ymax = .4
normalcdf(
invNorm(
tpdf(