The General Social Survey asked 1972 adults how many years of education they had. The sample mean was 13.37 years with a standard deviation of 3.13 years.

a. Construct a 98% confidence interval for the mean number of years of education.

b. Data collected in an earlier study suggests that the mean ten years ago was 13.26 years. A sociologist believes that the mean now is the same. Does the confidence interval contradict this belief? Explain.