00:01
Well, i'm going to give you my best shot in helping you on this one.
00:04
And so we know that the probability that at least one warranty occurs is 0 .45.
00:14
And we know that means that the probability that there are no warranty issues is 0 .55.
00:21
So we know that.
00:23
And then the question was weirded quite oddly.
00:27
And it says, consider the period until.
00:34
The fifth, having at least one, fifth time that you had at least one warranty month occurred.
00:48
And we want to find what is the probability that, given that we have this situation, what's the probability that we have exactly three months that are zero? so i had to think about this.
01:07
So we need to have three that are zero and we need to have five that have at least one, which means we need to have eight months.
01:18
Now, within those eight months, we need to have in that first group of seven months, there need to be three of these zeros.
01:35
And then we need four that are, and they could be in any order.
01:39
And we need four that we have at least one.
01:43
And then on the eighth month, we need to have this warranty problem that at least one...