Chapter 17 probability applications, The mth/probability.. sub-menu - part 1, Factorials, combinations, and permutations – HP 48gII User Manual
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Page 17-1
Chapter 17
Probability Applications
In this Chapter we provide examples of applications of calculator’s functions
to probability distributions.
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 list of MTH options is provided (see left-hand side figure below).
We have selected the PROBABILITY.. option (option 7), to show the following
functions (see right-hand side figure below):
In this section we discuss functions COMB, PERM, ! (factorial), RAND, and
RDZ.
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
−
=
+
−
−
−
=