Assume the sample mean for a random sample of size 25 was 300 and the std deviation (s) was 20. Form a 95% confidence interval on the mean. I set n =...

Assume the sample mean for a random sample of size 25 was 300 and the std deviation (s) was 20. Form a 95% confidence interval on the mean.

I set n = 25, s = 20, xbar = 300, & df = 24. But what mu am I testing on? Then I would use t = (xbar - mu) / (s / sqrt(n)).