Bell-shaped distribution

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. 1.From the Empirical Rule, what is a range of values that 95% of the students should graduate between?2.From the Empirical Rule, what is a range of values that 68% of the students should graduate between?3.From the Empirical Rule, what is a range of values that 99.7% of the students should graduate between?4.Suppose that the average height for college men is 66 inches. If the height distribution is bell-shaped, and 95% of the men have heights between 60 inches and 72 inches, what is the standard deviation of heights for this population? please show work