Question 860202: 4.) Convert the following test scores to z-scores and then decide which is the student’s best and worst area of performance.
a) Best:___________________________________ Worst:_____________________________
Test Score Mean Standard Deviation Z-Score
Oral
Interpretation 38, 40, 10, -.02
Persuasion 28, 20, 20,0.4
Theory Building 45, 30 ,20, .75
I have solved the z- scores but I am having a bit of difficulty understanding which the best or worst performance. This is a table and the score, mean, standard deviation, and z-score are given in that order by subject.
Answer by ewatrrr(24785)   (Show Source):
You can put this solution on YOUR website!
Hi,
z-scores tell the tAle as well. Some feel more comfortable using Percentages.
z-scores need not be converted to percentage to compare them:
done below to give more insight to the Standard Normal Curve.
Percentages given represent area under curve to the left of the z-score
Score Mean Standard Deviation Z-Score
Oral Interpret 38, 40, 10,  42%
Persuasion 28, 20, 20, 0.4 65%
Theory Building 45, 30 , 20, .75 77%
Below: z = 0, z = ± 1, z= ±2 , z= ±3 are plotted.
Note: z = 0 (x value the mean) 50% of the area under the curve is to the left and %50 to the right
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