Suppose that the average number of years to graduate at a university is 4 years, with a standard deviation of 0.5 years. Assume a bell-shaped distribution for years to graduate. According to the empirical rule, a. The range of values that 68% of the students should graduate is between and years. b. The range of values that 99.7% of the students should graduate is between and c. 96 of students should graduate between 3 and 5 years