posted by Lyndyc .
Find the Standard Deviation for this distribution of scores. Then find the z score for X=86. N=17
98, 92, 86, 84 , 76, 74 , 72 , 72, 72 , 70, 70, 66, 60 ,54, 32,30
Although you indicate n = 17, you only have 16 scores listed.
Find the mean first = sum of scores/number of scores
Subtract each of the scores from the mean and 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-mean)/SD
I'll let you do the calculations.