At a particular university, students' grades in introductory statistic classes are generally unimodal and skewed to the left with a mean of = 67 and a standard deviation of a = 16.1. (Round your answers to four decimal places, if needed.) (a) The distribution of students' grades is is left-skewed (b) If n = 35 students are selected at random, the distribution of the sample mean grade is approximately normal with a mean of and a standard deviation of (c) The probability that the sample mean grade for these 35 students is less than 69.0 is (d) If n = 35 students are selected at random, the distribution of the sample total grade is approximately normal with a mean of and a standard deviation of (e) The probability that the total grade for these 35 students is less than 2415.0 is