A standardized exam's scores are normally distributed. In a recent year, the mean test score was 1491 and the standard deviation was 312. The test scores of four students selected at random are 1910, 1230, 2190, and 1380. Find the z-scores that correspond to each value and determine whether any of the values are unusual.

Step-by-step explanation:

-Given the population mean is and  the standard deviation is , we calculate the z-scores using the formula:

#The z-score for 1910 can be calculated as:

#The z-score for 1230can be calculated as:

#The z-score for 2190 is calculated as follows:

#The z-score for 1380 is calculated as:

the answer will be the last one