User Guide

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( rnnrnnnn
rn
P −=+−−−=
Also, the number of combinations of n objects taken r at a time is
)!(!
!
!
)1)...(2)(1(
rnr
n
r
rnnnn
r
n
−
=
+−−−
=
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