statistics
posted by Lisa .
Measures of Central Tendency,variability, and postion
12th Grade math class.
organize the data 78,67,95,85,84,86,82,75,85,94,91,57,78,77,88,90,91,86,84,82,75,58,73,75. Then do 4 columns of Grades,Deviations,Squares,and ZScores

Find the mean first = sum of scores/number of scores
Subtract each of the scores from the mean for deviation. Square each difference. Find the sum of these squares. Divide that by the number of scores to get variance.
Standard deviation = square root of variance
Z score = difference/standard deviation
I'll let you do the calculations.