## anonymous 5 years ago 1. An animal clinic kept record of the life spans of certain poodles. The number of years the dogs lived are 8, 10, 12, 15, 17, and 13. What is the standard deviation of the poodle life spans?

1. anonymous

do you know the standard deviation formula?

2. anonymous

it should be around the sqrt(102/10)

3. anonymous

whats the formula

4. anonymous

phinx828--go back to the other question

5. Yuki

to find the SD, you need to know the formula $\sqrt({1 \over n} \sum {(x*-x_i)^2})$

6. anonymous

sqrt(107/10)*

7. anonymous

Here!

8. anonymous

thats confusing, i never saw that formula

9. Yuki

usually the steps are as follows 1), find x* which is the mean 2), list the square of mean deviations in your case, x*-8, x*-10, x*-12 ...etc 3), square each numbers you got in the list (x*-8)^2, (x*-10)^2, ... etc 4), add them up 5), divide them by the number of #s, in your case since you have 6 numbers, divide by 6 at this step, you will get a number called the "variant" SD is defined as the square root of the variant, so 6), square root the number you got

10. Yuki

rosette, do you need explanation how the formula works ?

11. anonymous

no