Chapter 15 probability distributions, The mth/probability.. sub-menu - part 1 – HP 49g+ User Manual
Page 154
Page 15-1
Chapter 15
Probability Distributions
In this Chapter we provide examples of applications of the pre-defined
probability distributions in the calculator.
The MTH/PROBABILITY.. sub-menu - part 1
The MTH/PROBABILITY.. sub-menu is accessible through the keystroke
sequence
„´. With system flag 117 set to CHOOSE boxes, the
following functions are available in the PROBABILITY.. menu:
In this section we discuss functions COMB, PERM, ! (factorial), and RAND.
Factorials, combinations, and permutations
The factorial of an integer n is defined as: n! = n
⋅
(n-1)
⋅
(n-2)…3
⋅
2
⋅
1. By
definition, 0! = 1.
Factorials are used in the calculation of the number of permutations and
combinations of objects. For example, the number of permutations of r
objects from a set of n distinct objects is
)
/(
!
)
1
)...(
1
)(
1
(
r
n
n
r
n
n
n
n
r
n
P
−
=
+
−
−
−
=
Also, the number of combinations of n objects taken r at a time is
)!
(
!
!
!
)
1
)...(
2
)(
1
(
r
n
r
n
r
r
n
n
n
n
r
n
−
=
+
−
−
−
=