Sammy the Statistics Student wanted to estimate the difference between

Sammy the Statistics Student wanted to estimate the difference between the population average time of his AM(x1) and PM(x2) commutes. Using 40 AM commutes and 31PM commutes, he found a 95% confidence interval for the difference of mean times of 3 to 16 minutes.

A) What can be said, if anything, about the two means at the 95% level of confidence and why?

B) What can be said, if anything, about the two means at the 90% level of confidence and why?

C) If he was being conservative in his calculation, what degrees of freedom would he have used and what critical value?