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.
