Listed below are the numbers of years it took for a random sample of college students to earn bachelor's degrees ...

Listed below are the numbers of years it took for a random sample of college students to earn bachelor's degrees(based on data from the National Center for Education Statistics). Construct a 90 % confidence interval estimate of mean time required for college students to earn bachelor's degrees. Does the confidence interval contain the value of 4 years? Is there anything about the data that would suggest that the confidence interval might not be a good result?

4 4 4 4 4 4 4.5 4.5 4.5 4.5 4.5 4.5 6 6 8 9 9 13 13 15