On a recent test, students had the following scores: 85, 100, 92, 96, 87, 94, 75. for these scores, find: a) mean b) variance = sum of (difference from the mean)^2 c) standard deviation = square root of the variance

A) Mean = [85+100+92+96+87+94+75] / 7 = 89.86

b) Variance = sumatoria (value - mean)^2 / (n-1)

{ (85 - 89.86)^2 + (100-89.86)^2 + (92-89.86)^2 + (96-89.86)^2 + (87-89.86)^2 + (94-89.86)^2 + (75-89.86)^2 } / (7-1) = 423.02/6 =70.5

c) Standard deviation = √variancia

= 8.40