I am working through a problem on CI for a sample mean and I cannot get the answer listed in the text I have. I am wondering if I am missing something or whether the text may be incorrect.
We are given a sample of 10 scores:
I get a mean of 44.5 and SD of 8.68 which is the same as the solutions listed. I also get a standard error of the mean of 2.75 which is the same as the solutions.
However I cannot get the final answer. We are asked to calculate a 95% CI for the mean. When I calculate the margin of error (standard error of the mean * tcritical) I get the answer
2.75*2.262=6.2. (I choose df= 9). Thus the CI I get is
38.3 - 50.7.
However, the text says it is
28.35-60.65. Am I missing something? I would be really grateful for any comments. Thanks.