00:01
Now here we have two little questions about the confidence intervals, right? the first one is you also find the sample size as suppose the sample size and you need to find it.
00:10
Needed to guarantee we can estimate a population proportion using a z interval with the margin of owning 3 % right? 0.
00:19
I mean 0 .3 as the margin of error at 95 % competition level, right? 95 % confidence level.
00:27
You know the margin of error is given by the z.
00:30
Score at corresponding to this confidence level, which in this case, of course, 2 .5 % at this square 2 .5 % multiplied by the square root of, you know, because we have no idea about the, we have no information about the possible population in proportion, right? so we have to use a conservative, conserved estimate.
00:56
So in other words, the standard deviation is given by half, multiplied by half divided by the sample size amr.
01:02
So if you do that, you will find this n to be given by the z score, which you look at the table to find to be given by 1 .96.
01:10
So it's 1 .96 over 0 .03 squared, multiplied by 1 over 4.
01:17
And do the calculation.
01:18
You found this to be given by 1 .96 divided by 0 .03, and then you square it, multiply by 0 .25...