Based on the performance of all individuals who tested between July 1, 2013 and June 30, 2016, the GRE Verbal Reasoning scores are normally distributed with a mean of 149.97 and a standard deviation of 8.49. (https://www.ets.org/s/gre/pdf/gre_guide_table1a.pdf).
(a) Consider all random samples of 36 test scores. What is the standard deviation of the sample means? (Round your answer to three decimal places)
(b) What is the probability that 36 randomly selected test scores will have a mean test score that is between 150 and 155?