The test scores for the girls who received their Australian Tertiary Admission Rank (ATAR) are normally distributed. In a recent year, the mean test score for the girls was 66.25 and the standard deviation was 2.50. The test scores of four girls selected at random are 66.50, 69.75, 72.50, and 60.75.

(a) find the z-score that corresponds to each value and

(b) determine whether any of the values are unusual.