Question

A sample of 53 night-school students' ages is obtained in order to estimate the mean age of night-school students. = 25.7 years. The population variance is 12.

(a) Give a point estimate for mu.

(b) Find the 95% confidence interval for mu (lower and upper limit).

(c) Find the 99% confidence interval for mu (lower and upper limit).

For (b) I ended up with 22.47 and 28.93 and for (c) I ended up with 21.45 and 29.95.