Ajournal 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 8.51 hours and a standard deviation of 2.05 hours. assume that the distribution of the number of hours of sleep for this group of students is approximately normal.
a. p(x> 12)=
b. p(8 c. find the value a for which p(x