A standardized exam's scores are normally distributed. In a
recent year, the mean test score was 1507 and the standard
deviation was 315. The test scores of four students selected at
random are 1900, 1260, 2220, and 1390. Find the z-scores that
correspond to each value and determine whether any of the values
are unusual. The z-score for 1900 is nothing. (Round to two
decimal places as needed.) The z-score for 1260 is nothing.
(Round to two decimal places as...