Which formula is used to calculate the standard deviation of sample data?
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n-1
100. ()*(3*3)*==(x-)
0 /6 -> * (37)*(
n-1

Step-by-step explanation:

In statistics, the standard deviation is a measure about the amount of variation of a dataset.

The variation is measured through comparison between each data and the mean of the dataset. This way, we could get a numerical information about how far are those values form the mean (which represents the central value).

The formula to find the standard deviation of a sample is

Where is the sample mean and is the total number of values there are.

In the formula you can notice the difference between each value () and the mean (), That's why the standard deviation is commonly use to measure variation.

Therefore, the answer is

a 4/6 = 9/12   not proportional

step-by-step explanation:

to find which are not proportional, we can use cross products

if it is true, they are proportional.   if it is not true, they are not proportional.

a 4/6 = 9/12

4* 12 = 6*9

48 = 54

not this is not proportional  

b 2/3 = 12/18  

2* 18 = 3 * 12

36 = 36

this is proportional

c 5/4 = 10/8  

5*8 = 4*10

40 = 40

this is proportional

d 7/5 = 35/25

7*25 = 5 * 35

175 = 175

is proportional