Permutation

Hello! This is Aliana and I’m going to talk about permutation.

Here’s a quick introduction. ;)

What it is Permutation?

A permutation of a set of distinct objects is an arrangement of objects without repetition, into a specific order. To permute a set of objects means to rearrange them.

Note: Value of N should and always be greater than the R value

Formula:

Only use the formula when you are arranging items in a specific order or the dash method. However, dash method most of the time works for all situations but the permutation formula can only be used if the question does not allow repetition and/or has no restrictions. If the question does allow for repetition and/or restrictions, you must use the dash method.

Basically:

Does not allow repetition and/has no restrictions = Permutation Formula or Dash Method

Does allow for repetition and/has restrictions = Dash Method

Example 1: How many three letter words composed from the 26 letters in the alphabet are possible if…

a)      No repetitions are allowed?

b)      Repetitions are allowed?

For cases that are asking for you to arrange a set of items which contains repeated items, then you must divide out those repetitions.

Total arrangements = 

Note: Where n is the total number of items and a!b!c!d!.... represents the repeated items.

Example 2: Find the number of distinguishable permutations using all all the letters in each word:

a)      BEGINNING                                                                          b) REFERRED

           

                    

c) MISSISSIPPI                                                          d) FREEZE but begin with Z

                   

 And that’s all. K bye ;)