00:01
So we have a scenario in which we have a probability of something rising, of a stock rising, i believe is the way it is determined.
00:09
And that probability that a does is 0 .41.
00:13
The probability that b does is equal to .59.
00:19
And the probability of if b, which means conditional on b, that a does is equal to 0 .58.
00:25
And we want to find in part a, we want to find what is the probability that at least one does.
00:31
So either a or b or possibly both.
00:35
And so we know in order to find that we would add the probability of each event, but then we have to subtract away that intersection.
00:45
And we don't know that yet.
00:47
But we can find it from this because this probability is equivalent to the probability of a intersect.
00:55
B divided by the probability of b.
00:59
And we know that the probability of a intersect b is something we don't know.
01:06
But we know the probability of b is 0 .59.
01:09
And we know that this quotient is equal to that 0 .58.
01:15
So the probability of that intersection has to equal the product of 0 .59 times 0 .58.
01:24
So that's our intersection.
01:28
So to answer this question up here, we're going to take that 0 .41 plus the 0 .59 and subtract away that intersection.
01:39
So 0 .41 plus 0 .59 minus that intersection...