00:01
So for this problem, to find our 99 % confidence interval for the difference in proportions, we'll do p -hat 1 minus p -hat 2, plus or minus z for a tail proportion of 0 .005 times the square root of p -bar times 1 minus p -bar times 1 over n1 plus 1 over n2, where p -bar is a bar, where p -bar is the pooled proportion.
00:33
So looking at our data, first we'll find p -hat 1, which is going to be equal to 986, let's say group 1 is the males.
00:42
We have 986 divided by 2153.
00:47
So that's 0 .458.
00:53
For p -hat 2, we have that that is going to be 923 divided by, excuse me, 2729.
01:01
Oh, oops, let me fix that there.
01:05
923 over 2729.
01:08
So that's 0 .338.
01:13
And then p -bar, the pooled proportion, is going to be 986 plus 923 divided by 2153 plus 2729.
01:22
Turn that into a decimal.
01:25
0 .391.
01:28
Then we just need to find what our z value is.
01:33
So looking, or i'll just use my software here to find that...