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)…321.

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

n Pr

= n(n 1)(n 1)...(n r + 1) = n! /(n r)

Also, the number of combinations of n objects taken r at a time is

n

 

n(n 1)(n 2)...(n r + 1)

 

n!



 

 

 

 

 

=

r!

= r!(n r)!

r

Page 15-1

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HP 49g Chapter Probability Distributions, MTH/PROBABILITY.. sub-menu part, Factorials, combinations, and permutations