HP 48gII Probability Distributions, Chapter, 1), 1)(n, = n(n, 2)...(n, r!(n − r), The MTH/PROBABILITY.. sub-menu- part, Factorials, combinations, and permutations

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

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 

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