In a random sample of 150 community college students, the mean number of hours spent studying per week is 12.75 hours and the standard deviation is 3.5 hours.

a) Assuming the distribution of the number of hours community college students study per week is normally distributed, what percent of the students in the sample study between 9.25 and 16.25 hours per week?

b) Approximately how many of the students (to the nearest whole student) in the sample study between 9.25 and 16.25 hours per week?