00:01
All right, your question is dealing with birth defects, and this is considered a binomial probability because there's only two possible outcomes, birth defect or no birth defect.
00:12
We consider each birth independent of the other, and we believe that the birth defect rate is going to remain the same.
00:20
So now, let's go ahead and move on to figuring out the question.
00:23
We're going to randomly choose five births, and we want to find the probability that at least one of those births had a defect.
00:30
The phrase at least, whenever you do something like this, always implies that you're going to use a complement.
00:40
A complement makes this a lot easier to do.
00:44
So what i'm going to do is say the complement of at least one birth defect would be one minus the probability of no birth defects.
00:59
And if you think about what that means, really what they were asking, probability of at least one means we have five and we could have one birth defect or we could have two or we could have three or we could have four or we could have five...