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Standardizing
Scores
Z-score
• # of standard deviations from the mean
• Formula :
Example: You are taking a test in your history
class. Your teacher tells you that the mean
grade was 80 and there was a standard
deviation of 6.07 points.
How many standard deviations from the mean is
your test score of 89?
Formula :
Substitute: (89-80)/6.07 = z-score
≈ 1.482
Conclusion: 89 is 1.482 standard deviations
above the mean.
Example: You are taking a test in your history
class. Your teacher tells you that the mean grade
was 80 and there was a standard deviation of 6.07
points.
How many standard deviations from the mean is
your test score of 69?
Formula :
Substitute: (69-80)/6.07 = z-score
≈ -1.812
Conclusion: 69 is -1.812 standard deviations
BELOW the mean.

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Standardizing scores

  • 2. Z-score • # of standard deviations from the mean • Formula :
  • 3. Example: You are taking a test in your history class. Your teacher tells you that the mean grade was 80 and there was a standard deviation of 6.07 points. How many standard deviations from the mean is your test score of 89? Formula : Substitute: (89-80)/6.07 = z-score ≈ 1.482 Conclusion: 89 is 1.482 standard deviations above the mean.
  • 4. Example: You are taking a test in your history class. Your teacher tells you that the mean grade was 80 and there was a standard deviation of 6.07 points. How many standard deviations from the mean is your test score of 69? Formula : Substitute: (69-80)/6.07 = z-score ≈ -1.812 Conclusion: 69 is -1.812 standard deviations BELOW the mean.