00:01
So in this measure we need to use the, because basically we want to find what is the 99 % confidence interval for the true difference between the means.
00:11
But we should assume here that the population variances are equal.
00:15
This means that the first thing that we are going to compute is the sample variance here, considering that in the population they are the same.
00:24
So the formula to find this is equal to this sample size minus 1 for the first group times the standard deviation for the group squared.
00:33
Then we repeat the same thing for the other group.
00:35
So we are going to get this.
00:37
And then we divide this by the sum of these two values, so 28.
00:42
So this will give us, that's the sample proportion, is 728.
00:47
Now we are going to compute the confidence interval s.
00:50
The difference between the sample means, and here we should use the t -student distribution to find this confidence interval, which basically means that we are going to find the critical value for this confidence interval in the t -student distribution with degrees of freedom equals to this denominator here, which is the sum of the sample sizes minus 2...