Answer:
And we are 95% confident that the true difference means are between
Step-by-step explanation:
We know the following info:
sample mean for group 1
sample mean for group 2
sample standard deviation for group 1
sample standard deviation for group 2
sample size group 1
sample size group 2
We want to find a confidence interval for the difference of means and the correct formula to do this is:
Now we just need to find the critical value. The confidence level is 0.95 then the significance is and . The degrees of freedom are given by:
The critical value for this case would be :
And replacing into the confidence interval formula we got:
And we are 95% confident that the true difference means are between
I don't understand the question
D
7•4 =28, -5•0 =0... 28+0=28