Respuesta :
We can see that a security system uses a four-letter password (r=4), but no letter can be used more than once, and the system can use all 26 letters of the alphabet (n=26).
As a result, we must use permutation to compute the number of possible passwords. As a result, the total number of possible passwords is 358800.
Step-by-step solution to the question:
P(n, r) = ?
P(n, r) = P(26, 4)
P(n, r) = [tex]\frac{26!}{(26-4)!}[/tex]
= 358800
What is Permutation?
A permutation is a specific arrangement of objects. Set members or elements are arranged in a sequence or linear order here.
For example, the permutation of set A={1,6} is 2, such as {1,6}, {6,1}. As you can see, there are no other ways to arrange the elements of set A.
To know more about Permutation, visit: https://brainly.com/question/1216161
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