00:01
This problem says how many two -letter code words can be formed from the letters w, c, m, and j if the letters can be repeated, and also we want to answer the same question if adjacent letters must be different.
00:11
And when we say adjacent letters must be different, since we only have two letters, if they're adjacent, they're next to each other.
00:16
So that's basically saying that no repetition is allowed.
00:19
So for our first question where repetition is allowed, if we're trying to figure out a two -letter code or all those possibilities, for the first letter of this code, we're going to have every letter available to.
00:30
Us, wcm and j.
00:31
So that means there's four total possibilities.
00:34
And if repetition is allowed, it doesn't matter if we use w for the first blank and then use w again or whatever the letter is.
00:41
So we're going to have four choices for the first letter, but we're also going to have four choices for the second letter.
00:45
And to figure out the total number of possibilities, you use the fundamental counting principle, which just means you multiply all of your options together...