## chocolatechip_543 Group Title The following table shows the probability distribution for a discrete random variable. X 13 16 18 21 23 25 26 31 P(X) 0.07 0.21 0.17 0.25 0.05 0.04 0.13 0.08 The mean of the discrete random variable X is 20.59. What is the variance of X? Round your answer to the nearest hundredth. 2 years ago 2 years ago

1. telliott99 Group Title
2. hal_stirrup Group Title

$s2 = Σ ( x _{I} - x )2 / ( n - 1 )$

3. hal_stirrup Group Title

are you there??

4. chocolatechip_543 Group Title

yes

5. chocolatechip_543 Group Title

can you explain the equation a bit?

6. hal_stirrup Group Title

sure lets star with $\sum_{i=1}^{n}$

7. hal_stirrup Group Title

do you understand what this means?

8. chocolatechip_543 Group Title

yes

9. hal_stirrup Group Title

good then$x_{i} -x$ xi is each value of your x value . -x really i cant use xbar because the keyboard is limited .. x bar is the average= $xbar=\sum_{i=1} x _{i}/n$

10. hal_stirrup Group Title

we are assuming that you have sample and not population as well !!!!

11. chocolatechip_543 Group Title

alright..I'm a little lost now

12. hal_stirrup Group Title

tell me where.

13. chocolatechip_543 Group Title

at the last part you posted

14. hal_stirrup Group Title

"we are assuming that you have sample and not population as well" that

15. chocolatechip_543 Group Title

yes and before that

16. hal_stirrup Group Title

look. inorder to help you you need to be clear as to where are you not understanding . so i can help you better. thanks

17. chocolatechip_543 Group Title

I'm sorry, I just don't understand it.

18. hal_stirrup Group Title

no need to be sorry . :)

19. hal_stirrup Group Title

have you done statistics before ?

20. chocolatechip_543 Group Title

no, but this is in my algebra 2 work

21. hal_stirrup Group Title

thats cool/

22. hal_stirrup Group Title

do you now how to get the mean?

23. chocolatechip_543 Group Title

yes

24. hal_stirrup Group Title

ok so were half way.

25. hal_stirrup Group Title

lets talk concept first. is that ok?

26. chocolatechip_543 Group Title

sure

27. hal_stirrup Group Title

variance is the distance from the mean measured in squares. |dw:1343956195413:dw|

28. hal_stirrup Group Title

in you r case you have many data points. so really your job is fine all the distance from the mean and then sum them up and divide by the number of data point and minus 1.

29. hal_stirrup Group Title

s2=Σ(xI−x)2/(n−1) thats what this formula say.

30. chocolatechip_543 Group Title

oh alright

31. hal_stirrup Group Title

share what your thinking if you like?

32. hal_stirrup Group Title

if you like to , be my fan and send my question and thoughts if you want and dont forget to click on best response . thanks @chocolatechip_543