Question

anyone know about summation notations? How do you get the number your dividing by?

Answer 1

a little more information would be helpful

Answer 2

if this is part of a problem, knowing the problem would be useful :)

Answer 3

\[\sum\]This is sigma, a pretty cute symbol standing for summation. For some reason, he's obsessed with infinity, though.

Answer 4

what do you need? \[(X-X)^2 for the following values of X: 5,7, 2, 1, 3, 6\]

Answer 5

5-5=0
7-7=0
.....

Answer 6

what do you put on the bottom of the equation? How do you know what number to use

Answer 7

As Jack Sparrow would say: "You're not making any sense, mate."

Answer 8

lol

Answer 9

if your talking about the index, it tends to be the 1

Answer 10

\[\sum_{i=1}^{n}(x_i-x)^2\]maybe?

Answer 11

the top number is the number of elements you have in the sequence

Answer 12

the bottom tends to tell you where to start at

Answer 13

and sum(x^2) = n(n+1)(n+(n+1))/6

Answer 14

\[\sum_{i=1}^{n}x_{i}=x_{1}+x_{2}+...+x_{n}=\frac{1}{2}n(n+1)\]

Answer 15

x^3 is the square of x ;)

Answer 16

Sigma(X-X)^2 for the following values of 5,7,2,1,3,6
Note: The second X has an -over the top of it. Can anyone tell me how you know what you use on the bottom of the division

Answer 17

x bar tends to be notation for mean

Answer 18

add up your data set and divide by ... there is 6 of them so .. divide it by 6 to get the valueof x bar

Answer 19

if your going for variance; it depends on sample or population

Answer 20

the data set here suggests a population since it doesnt state otherwise

Answer 21

Oh okay. That's exactly wahat I was needing to know. Thank you so so much!

Answer 22

for a sample, we use a degree of freedom, usually n-1

Answer 23

for the population; just n :) youre welcome

Answer 24

also of note: \(\bar x\) is usually used for sample mean whereas, \(\mu\) is used to indicate a population mean

Answer 25

sample tends to look like this
\[\frac{\sum(x-\bar x)^2}{n-1}\]
and population like this
\[\frac{\sum(x-\mu x)^2}{N}\]

Answer 26

typoed that last bit .... but your smart enough to read thru it