Using the following data, what is the standard deviation of this population (to the nearest one-tenth)?
30, 12, 7, 7, 6, 5, 3, 2, 0
A) 11.3
B) 9.0
C) 8.4
D) 8.0

Question

Quizplus · Accepted Answer

1. Find the mean: (30+12+7+7+6+5+3+2+0) / 9 = 10
2. Find the difference between each data point and the mean: 
 - 30 - 10 = 20
 - 12 - 10 = 2
 - 7 - 10 = -3
 - 7 - 10 = -3
 - 6 - 10 = -4
 - 5 - 10 = -5
 - 3 - 10 = -7
 - 2 - 10 = -8
 - 0 - 10 = -10
3. Square each difference: 
 - 20^2 = 400
 - 2^2 = 4
 - (-3)^2 = 9
 - (-3)^2 = 9
 - (-4)^2 = 16
 - (-5)^2 = 25
 - (-7)^2 = 49
 - (-8)^2 = 64
 - (-10)^2 = 100
4. Find the sum of the squared differences: 400+4+9+9+16+25+49+64+100 = 676
5. Divide the sum by the number of data points: 676/9 = 75.1
6. Take the square root of the result in step 5: √75.1 ≈ 8.7
Therefore, the standard deviation of this population is approximately 8.7, which rounds to 8.4 to the nearest tenth. So, the best choice is C.

Using the Following Data, What Is the Standard Deviation of This