Question

find the standard deviation for the following set of info; 1 1 1 1 1 1 1 1

Answer 1

help me please

Answer 2

wouldn't it be zero since the set is all the same numbers

Answer 3

i guess but how do you find standard deviation ex 3 5 5 7 7 9

Answer 4

it's a little confusing you take the square of all the numbers in the set and find the mean of that and you subtract it by the normal mean of the set squared and you take the square root of all of that

eg.
[(9+25+25+49+49+81)/6] - (3+5+5+7+7+9/6)^2 and whatever you get you take the square root

Answer 5

thats not how i learnt it ....

Answer 6

it's been awhile i just googled it if you have a better way to explain it then go ahead lol

Answer 7

i'm basically taking the square root of var(x)

Answer 8

find the mean of the set

find the difference between the mean and each datapoint

square those differences and add em up

\[\sum (x-\mu)^2\]

divide by n (for population) ; or n-1 (for samples)

\[\frac{\sum (x-\mu)^2}{N,(n-1)}\]

this is variance; standard deviation is just the sqrt of variance

Answer 9

to find the mean do i square the numbers

Answer 10

no, to find the mean you add the numbers and divide by how may there are

Answer 11

\[mean(a_1,a_2,a_3,...,a_n)=\frac{a_1+a_2+a_3+...+a_n}{n}\]

Answer 12

ok then what

Answer 13

go to the next step ...

Answer 14

find the difference between the mean and the data points

Answer 15

i dont understand data point

Answer 16

the numbers you are given are the data results of the tests/experiments/goings-on

Answer 17

you are given a set of numbers, of data points, to manuver with

Answer 18

can you show me

Answer 19

can i show you what your numbers are?

Answer 20

3 5 5 5 7 7 8

Answer 21

ok, and the mean of those is?

Answer 22

opps take off one 5 and replace 8 wiith 9

Answer 23

ok 6

Answer 24

subtract the mean, you say its 6, from each number and rewrite the set

Answer 25

it doesnt matter if you subtract the mean from the number or the number from the mean; its the difference we want; sign doesnt matter

Answer 26

-3 -1 -1 1 1 3 ok

Answer 27

those look fine

now square them

Answer 28

9 1 1 1 1 9

Answer 29

good, now add those all together

Answer 30

22

Answer 31

almost there;

do you know if this data represents a sample of a population?

Answer 32

no

Answer 33

well, when you know if its a pop. (divide by the number of data points) or a samp (number of data points minus 1)

you have 6 numbers; so lets assume its a population just for closure :)

22/6 = variance

sqrt(22/6) = standard deviation

Answer 34

if it was a sample; wed of divided by 5 in this case

Answer 35

ok thnks so much!!!!!!!:):) u rock

Answer 36

oure welcome, hope it helped :)