A standardized exam's scores are normally distributed. In a recent year, the mean test score was 1483 and the standard deviation was 318 . The test scores of four students selected at random are 1900, 1200, 2170, and 1380 . Find the $z$-scores that correspond to each value and determine whether any of the values are unusual.
The $z$-score for 1900 is 1.31
(Round to two decimal places as needed.)
The $z$-score for 1200 is
(Round to two decimal places as needed.)

Step 1 ：The problem provides us with the mean test score (\(\mu\)) of 1483, the standard deviation (\(\sigma\)) of 318, and a specific test score (\(X\)) of 1200. We are asked to find the z-score for this test score.

Step 2 ：The z-score is a measure of how many standard deviations an element is from the mean. It is calculated using the formula: \(Z = \frac{X - \mu}{\sigma}\)

Step 3 ：Substituting the given values into the formula, we get: \(Z = \frac{1200 - 1483}{318}\)

Step 4 ：Solving the above expression, we find that the z-score for the test score of 1200 is approximately -0.89

Step 5 ：Final Answer: The z-score for 1200 is \(\boxed{-0.89}\)