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?