To find the standard score, or "z-score," first determine the score, mean and standard deviation of the set. The z-score is calculated using the formula "z = (x - u) / o," where x is the recorded score, u is the mean score and o represents the standard deviation.
Continue ReadingFor example, consider that Greg recorded a test score of 80 out of 100 on his Calculus exam. Among the 100 students in the class, the mean score was 65 and the standard deviation was 10. When plugged into the formula, these variables produce a z-score of 0.67. The percentage of those scoring above Greg could then be determined by referring to the standard normal distribution table.
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