Question

MIKE IS CHOOSING A 3 LETTER PASSWORD FROM THE LETTERS A, B, C, AND D. THE PASSWORD CANNOT HAVE THE SAME LETTER REPEATED IN IT. HOW MANY SUCH PASSWORDS ARE POSSIBLE?

Answer 1

There are 4 possible letters to start with.

The pass word is 3 letters long.

The first letter can be A, B, C, D = 4 different letters.

The 2nd letter can be 4 - 1 = 3 letters ( Can't have repeats)

The 3rd letter can be 3-1 = 2 letters ( no repeats)

Number of possible passwords = 4 x 3 x 2 = 24