a survey among freshmen at a certain university revealed that the number of hours spent studying the week before final exams was normally distributed with mean 23 and standard deviation 9. use the cumulative normal distribution table to answer the following. (a) find the 94th percentile of the number of hours studying. (b) find the 29th percentile of the number of hours studying. (c) between what two values are the middle 84% of the hours spent studying?