Permutations with Repetitions and Restrictions

09/17/15

Today's lesson is about permutations that includes repetitions and restrictions. We cannot use the permutation formula since we are dealing word problems that can have either repetition or a restriction.We can only use the dash method because it all works in all situations.

Example:
How many 5 letter word can be formed using the letters m, a, g, i, c allowing for repetition of the letters?

Since we need 5 locations
_____  •   _____  •  _____  •   ____  •  _____ (dash method)

There are 5 letters that can be used to fill the first location. Repetition is allowed, the same 5 letters can be used. 
__5___  •   __5___  •  __5___ •__5___  •   __5___  = 3, 125 arrangements