00:01
We have been given some sample data.
00:02
Sample size n is 400.
00:05
Out of these, 172 had kids.
00:09
We want a confidence interval for the population proportion of people with kids.
00:14
My formula will be p -hat, sample proportion, point estimate, plus and minus the margin of error.
00:21
Error.
00:22
Z root p hat 1 minus p hat over n.
00:27
So we have n, we need p hat, which is the proportion of our sample that had kids, 172, out of 400, which in decimal form is 0 .43.
00:39
And we need z, which we get from the level of confidence.
00:43
Now according to the central limit theorem, if i took every sample of 400 people, found the proportion to have kids, and plotted all of those out, i would get something approximately normal.
00:55
Our sample proportion is somewhere on this curve...