At a particular university, students' grades in introductory statistic classes are generally unimodal and skewed to the left with a mean of = 64 and a standard deviation of = 18.2.(Round to 2 decimal places for all z-values and round all other answers to 4 decimal places, if needed.) (a) The distribution of students' grades is is approximately normalis exactly normalmay or may not be normalis left-skewedis right-skewed. (b) If n = 34 students are selected at random, the distribution of the sample mean grade is approximately normalnot normalleft-skewedright-skewed with a mean of and a standard deviation of . (c) The probability that the sample mean grade for these 34 students is less than 68.0 is . (d) If n = 34 students are selected at random, the distribution of the sample total grade is approximately normalnot normalleft-skewedright-skewed with a mean of and a standard deviation of . (e) The probability that the total grade for these 34 students is less than 2312.0 is