At a particular university, students' grades in introductory statistic classes are generally unimodal and skewed to the left with a mean of μ = 68 and a standard deviation of σ = 17.2. (Round your answers to four decimal places, if needed.)
(a) The distribution of students' grades is is approximately normal is exactly normal may or may not be normal is left-skewed is right-skewed.
(b) If n = 30 students are selected at random, the distribution of the sample mean grade is approximately normal not normal left-skewed right-skewed with a mean of ? and a standard deviation of .
(c) The probability that the sample mean grade for these 30 students is less than 72.0 is .
(d) If n = 30 students are selected at random, the distribution of the sample total grade is approximately normal not normal left-skewed right-skewed with a mean of ? and a standard deviation of .
(e) The probability that the total grade for these 30 students is less than 2160.0 is .
