Probability Calculations; Factorial; Permutations - HP 10bII+ User Manual

If BEST FIT is selected, the 10bII+ calculates the best fit when
\T
is pressed. When selected, BEST FIT flashes briefly, followed by the chosen fit. The
selected regression will remain set until a new one is selected, or the statistics memory is
cleared.
When the statistics memory is cleared using
back to LINEAR.

Probability Calculations

In many probability calculations, specific methods of counting possible outcomes are required
as part of a process to determine the likelihood of certain results. The three main operations
that allow this are:
!

factorial

•
P
•

permutations

n r
C
•
combinations
n r
Factorial
Factorial (!) is a mathematical operator that instructs you to multiply the current number by all
previous whole numbers. Writing out so many numbers can be cumbersome, so
mathematicians use ! to signify this process. For example:
5! is equivalent to 5 x 4 x 3 x 2 x 1 = 120.
On the 10bII+, the input value n must be within -253 < n < 253. The gamma function is used
to calculate n! for non-integer or negative values.
Permutations
The nPr function calculates the number of different arrangements, or permutations, of n items
taken r at a time. No item can occur more than once in a set of r items, and different orders
of the same r items are counted separately. This is calculated using the formula:
PERMUTATIONS
126 Statistical Calculations
\t
n!
=
----------------- -
n r
( )!
–
\Z \W
,
, the current regression model is set
, or