00:01
For this problem to begin, i'll note that since we have sample sizes, which are both less than 30, and we don't know the population standard deviations, we'll construct our confidence interval using t values.
00:17
So our 99 % confidence level, or confidence interval here, is given by a little bit of a lengthy formula.
00:28
It's going to be sample mean 1 minus sample mean 2, plus or minus, the critical t.
00:37
Value for n1 plus n2 minus 2 degrees of freedom and a greater than a probability of 0 .005 times the square root of n1 minus 1 times variance 1, sample variance 1 plus n2 minus 1 times sample variance 2 divided by n1 plus n2 minus 1 times sample variance 2 divided by n1 plus n2 minus 2 times the square root of 1 over n1 plus 1 over n2.
01:28
We have that n1, let's see here, we have a sample of 20 men, and we have a sample of 25 women.
01:39
So, n1 is 20, and 2 is 25.
01:43
So the number of degrees of freedom that we'd want to use would be 45 minus 2, so it would be 43 degrees of freedom.
01:56
Now, since we have 43 degrees of freedom, there are a few different approaches that you might see for how we approach, or how we do this.
02:05
It really depends on sort of what table you're expected to be using, if you're expected to be using a table at all.
02:11
For instance, you can see that on this t table, i have 40 degrees of freedom, which would be a decent estimate.
02:17
On this table, i end at 30 degrees of freedom...