00:01
Hi there, so for this problem, we are told that a clinical trial test a method designed to increase the probability of conceiving a girl.
00:12
In this study, 320 babies were born, so we are given the value of what we are going to call an 320 and 20 and 272 of them were going to be.
00:32
Girls.
00:34
So the number of girls were 272.
00:45
And use the sample data to construct a 99 % confidence interval.
00:52
So we have 99 % confidence.
00:58
Yes, of girls being born.
01:02
So what we need to obtain is the confidence interval for the population.
01:06
Proportion.
01:08
So that confidence interval is going between the two values and the following two values.
01:15
So we're going to have p, which is going to be the sample proportion, this minus seed of alpha divided by 2.
01:28
And this times the square root of again the sample proportion, this times 1 minus 1.
01:40
And sample proportion again, this divided by the number.
01:46
And in this case, which in this case is given, 320.
01:50
And for the other value, we will have the same, but in this case we have plus the same values, just like this.
02:08
So, okay, so when we need to determine third is the sample proportion.
02:12
So the sample proportion that we're calling here, p -haz.
02:16
Is just equal to the number of girls divided by the number n so that will be 272 divided by 320 so from this we obtain a value of 0 .85 okay now with that said we know that for a 90 % confidence interval gatma and alpha, sorry, it takes a value of 0 .01.
02:59
And you can search for the values for that alpha that will give us that seed of in this case, because it is alpha.
03:11
But if i do, so there will be 0 .005.
03:16
The value for this is 2 .57 and 50.
03:24
Okay, so the possible two values that we're going to have in this interval are 0 .85 using this equation in here, so what will have? 0 .85 minus 2 .5758 times the square root of b hat, which is 0 .85 times 1 minus 0 .85.
04:04
This divided by 320 and we take the square root of this...