hi, please help this probability and statistics questions with clear steps and details, thank you . if you cannot find the answer, please give a reason for it.

The time it takes for a math professor to mark his midterm test is normally distributed with a mean of 20 minutes and a standard deviation of 8 minutes. Answer Questions 1-4. Question 1: (1 Mark) Denote X to be the mean time for the math professor to mark his midterm test for a random sample of 100 students in his class. Compute the mean of the sampling distribution of I? for the sample. Question 2: {1 Mark) Compute the standard deviation of the sampling distribution of the mean time I? in Question 1. Question 3: (1 Mark} What is the probability that he needs more than 30 hours to mark the midterm tests for the sample of 100 students in Question I? Question 4: (1 Mark) Assume now that the mean and the standard deviation of the time it takes for a math professor to mark his midterm test remain to be 20 minutes and 8 minutes, respectively, but with some unknown distribution. For the sample of 100 students, what is the probability that he needs more than 30 hours to mark the midterm tests