00:01
So it looks like maybe you need help looking at the chart.
00:03
And the chart actually already has calculated the 95 % confidence interval for each.
00:09
It was taking the mean and then plus or minus.
00:12
And then it's going to use a t value with .025 in the upper tail and n minus 1 degrees of freedom here, and it will take the sample standard deviation divided by the square root of n.
00:26
Now, they have supplied you with the standard error.
00:31
So they're actually telling you that the standard error, say, for females.
00:36
So let me just quick look back at your chart.
00:37
The standard error for females is .16327.
00:41
So let me go down here, .16327.
00:48
And we know that that is equal to the sample standard deviation divided by the square root of n.
00:53
So we could actually go back and figure out the sample size.
00:56
It says the standard deviation is 2 .14125, 2 .14125.
01:06
And so doing some l draw, we could find that n would equal that 2 .14125 divided by that .16327.
01:17
So if i needed to show that, and then this quantity would be squared.
01:23
And so we have 2 .14125 divided by .16327 and then square that quantity.
01:35
So it looks like that sample size was actually 172 people.
01:42
And so just looking at the chart, that's how these were calculated.
01:45
So this actually used the sample standard deviation divided by 172, and it calculated this out...