The composite scores of individual students on the ACT college entrance examination in 2019 followed a Normal distribution with mean 20.8 and standard deviation 5.8.

a) What is the probability that a single student randomly chosen from all those taking the test scores 22 or higher?

b) Now take an SRS of 50 students who took the test. What is the probability that the mean score of these students is 22 or higher?

c)What is the probability that the mean score of an SRS of 100 students is 22 or higher