The Graduate Record Examination (GRE) is a test required for admission to many US graduate schools. Students' scores on the quantitative portion of the GRE follow a normal distribution with mean 150 and standard deviation 8.8. (Source: http://www.ets.org/ .) Suppose n=16 randomly selected students take the GRE on the same day. What is the probability that the mean score on the quantitative portion of the GRE is at least 157? [Hint: what is the distribution of x ?] 0.0007 0.999 0.213 0.787.