"An Analysis of the Study Time-Grade Association," published in Radical Pedagogy in 2002, looked at self-reported study time for the course, in hours per week, by 140 students enrolled in an Introductory Psychology course. Times had mean 3 hours and standard deviation 2.6 hours.

a. The article reports that according to the National Survey of Student Engagement, the Carnegie Foundation benchmark is 6 hours of study per week for a course that meets three hours a week. Standardize the sample mean time and explain why we can consider it to follow the z distribution.

b. Could the difference between sample mean study time (3 hours) and recommended study time (6 hours) have come about by chance in the process of sampling? Explain.