FIGURE 7-
Calculating the Percentile for a Negative z Score
As with positive z scores, drawing curves helps us to determine the appropriate percentage for negative z scores. For a negative z score, we subtract the percentage between the mean and that z score from 50% (the percentage below the mean) to get the percentage below that negative z score, the percentile. Here we subtract the 46.56% between the mean and the z score of –1.82 from 50%, which yields 3.44%.
Calculating the Percentile for a Negative z Score
As with positive z scores, drawing curves helps us to determine the appropriate percentage for negative z scores. For a negative z score, we subtract the percentage between the mean and that z score from 50% (the percentage below the mean) to get the percentage below that negative z score, the percentile. Here we subtract the 46.56% between the mean and the z score of –1.82 from 50%, which yields 3.44%.