66. The scores of eighth-grade students on the National Assessment of Educational Progress (NAEP) mathematics test in 2007 have a distribution that is approximately normal, with mean and standard deviation .
Choose one eighth grader at random. What is the probability that his or her score is higher than 281? Higher than 316?
Now choose an SRS of four eighth graders. What is the probability that their mean score is higher than 281? Higher than 316?