00:01
All right, so for this problem, to begin, we know that we can find our confidence interval by taking our point estimate for the proportion, which i use the symbol p hat to represent, plus or minus a margin of error term.
00:14
Now, the margin of error term, we find using a critical z value for if we're looking for 1 minus alpha percent confidence interval, we would have the z score for alpha over 2.
00:27
In this case, since we're looking for 90 % confidence, that would mean that 1 minus alpha would be 0 .1.
00:34
So we want 0 .05 as the tail proportion for our critical z value.
00:40
Then we multiply that by what would be the standard error of the sample proportion, which would be p hat times 1 minus p hat divided by n, where n is the total sample size.
00:52
So we first need to find our point estimate for the proportion p hat.
00:56
So, calculating that out, we know that the sample proportion, actually, it's just given to us explicitly, the sample proportion is 0 .1, or 10 % of the respondents.
01:09
We know that the sample size is equal to 100.
01:15
And we can find the critical z score using any number of methods.
01:19
You can use a table of values.
01:20
I'm just going to use my software here...