00:01
In this question, we're given that a die is wrote four times, and we want to find the probability of two ones, one two and one three.
00:09
So it's something like this, one, one, two, three.
00:13
Now take note that it could be one, two, one, three, so and so forth.
00:17
So what are the total number of different ways to arrange one, one, two, three? that will be four factorial over.
00:25
Now, take note that these two ones are repeats of each other, right? so over 2 factorial and that would be 12 ways to arrange this.
00:35
So there are 12 cases of arranging this guy, 12 mutually exclusive cases.
00:53
So that is either this case of probability of 1, 1, 1, 2, 3 or, now in probability, all is plus, or 1, 2, 1, 3, so on and so forth, up to the 12 case of possibly, possibly, 3211...