A journal published a study of the lifestyles of visually impaired students. Using diaries, the students kept track of several variables, including number of hours of sleep obtained in a typical day. These visually impaired students had a mean of 9.77 hours and a standard deviation of 2.15 hours. Assume that the distribution of the number of hours of sleep for this group of students is approximately normal. Complete parts a through c. a. p(x>12)=

b. p(8
c. Find the value a for which P(x