For a 4-units class like Statistics, students should spend average of 12 hours per week studying for the class. A survey was done on students, and the distribution of total study hours per week is bell-shaped with a mean of 13 hours and a standard deviation of 3 hours. Use the Empirical Rule to answer the following questions. a) 95% of the students spend between and hours on this class. b) What percentage of the students between 10 and 19 hours on this class? % c) What percentage of the students below 22 hours?