Question

in how many ways can the letters a b c d and e be arranged for a three letter security code if letters can be repeated?

Answer 1

In order to determine the number of arranges, or permutations, use the following formula:

P = n!/(n - r)!

where n is the number of available letters (n = 5), and r the number of letter for the combinations (r = 3). Replace these values into the previous formula:

P = 5!/(5 - 3)!

P = 5!/2!

P = 1·2·3·4·5/1·2

P = 120/2

P = 60

Hence, there are 60 ways of arranging three letter from a group of five letters, for the security code.