00:01
We have been given some sample data.
00:02
Sample size n is 800 actually.
00:06
Not everybody responded.
00:07
They sent it to 2800 people, but only 800 responded.
00:11
Out of these 800, 640 were satisfied with their new computer.
00:17
We want a confidence interval for the population proportion.
00:20
The formula we're going to use is p -hat, point estimate, sample proportion, plus and minus the margin of error, z root p -hat, 1 minus p -hat, over n.
00:33
So we have n.
00:34
P -hat is the proportion of the sample that meet criteria.
00:38
640 out of 800, which is 0 .8.
00:43
We get z from the level of confidence.
00:46
Initially, this is a binomial experiment.
00:48
N independent trials.
00:50
Two outcomes, they meet the criteria or they don't.
00:53
We get the same probability p, population proportion, for each customer is satisfied...