Operation Manual

Chapter 13: Inferential Statistics and Distributions 248
invT(
invT( computes the inverse cumulative Student-t probability function specified by Degree of Freedom,
df for a given Area under the curve.
invT(area,df)
tpdf(
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:
tpdf(x,df)
tcdf(
tcdf( computes the Student-t distribution probability between lowerbound and upperbound for the
specified df (degrees of freedom), which must be > 0.
tcdf(lowerbound,upperbound,df)
Note: For this example,
Xmin = L4.5
Xmax = 4.5
Ymin = 0
Ymax = .4
fx
 df 1+/2
 df 2
---------------------------------
=
1 x
2
/df+
df 1+/2–
df
-----------------------------------------------