please perfect answer

3. a. How wide (what is the range) is the 95% confidence interval about a sample mean of 25 when s =4 and N= 4? b. How much smaller is the 95% confidence interval about a sample mean of 25 when N is increased to 16 (s = 4)? c. Compared to your answer in part a, how much smaller is the 95% confidence interval about a sample mean when N remains 4 and s is reduced to 2