A history professor gives a quiz to his class and records the following scores: 13, 11, 11, 9, 12, 13, 16, 14, 11, 10, 8, 13, 20. The variance for this distribution is _________. Assume sample scores.
A) 162.38
B) 9.01
C) 9.76
D) 9.60

Question

Quizplus · Accepted Answer

1. Find the mean: (13+11+11+9+12+13+16+14+11+10+8+13+20) / 13 = 12
2. Subtract each score from the mean: -1, -1, -1, -3, 0, 1, 4, 2, -1, -2, -4, 1, 8
3. Square each result: 1, 1, 1, 9, 0, 1, 16, 4, 1, 4, 16, 1, 64
4. Find the sum of the squared differences: 118
5. Divide by the number of scores minus 1: 118 / 12 = 9.76

A History Professor Gives a Quiz to His Class and Records