If a random variable X has a Normal distribution with mean M and variance S2, then
Z = (X - M)/S
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Yes, although the z-scores associated with p-values of 0.01 and 0.05 have special significance, perhaps mostly for historical reasons, all possible z-scores from negative infinity to positive infinity have meaning in statistical theory and practice.
A Z score of 300 is an extremely large number as the z scores very rarely fall above 4 or below -4. About 0 percent of the scores fall above a z score of 300.
z = 1.281551
To find Stacey's first test score, we can use the formula for average: (sum of all scores) / (total number of scores). Stacey's total score on three tests is 84 x 3 = 252. Her last two test scores total 79 + 93 = 172. To find her first test score, we subtract the total of the last two tests from the total score: 252 - 172 = 80. Therefore, Stacey's first test score was 80.