## anonymous one year ago second part @jim_thompson5910

1. anonymous

2. jim_thompson5910

for the first column, under the $$\large x_i - \bar{x}$$, you will subtract the mean from each score (score minus mean)

3. anonymous

so it will be 90-90,90-90,90-80,90-100,etc @jim_thompson5910

4. jim_thompson5910

yes and the results will all go in that column

5. anonymous

are u sure its not the mean -score @jim_thompson5910

6. anonymous

hello

7. jim_thompson5910

it's score - mean

8. jim_thompson5910

that's what the xi - xbar means xi is the score

9. jim_thompson5910

|dw:1433566821653:dw|

10. jim_thompson5910

|dw:1433566832765:dw|

11. anonymous

so some will be negative @jim_thompson5910

12. jim_thompson5910

|dw:1433566847436:dw|

13. jim_thompson5910

yes it's normal to have negative differences

14. anonymous

so how I find the total? @jim_thompson5910

15. jim_thompson5910

you add up all of the numbers in the column to get the total

16. jim_thompson5910

you'll have 3 totals (one per column)

17. anonymous

the numbers I got were 0 0 -10 10 9 -9 8 and -8 and the total was 0 @jim_thompson5910 if this is correct I am ready to find the M.A.D

18. jim_thompson5910

now take the absolute value of each result that will form the next column over

19. jim_thompson5910

|0| = 0 |0| = 0 |-10| = 10 etc etc

20. anonymous

so will |10| be -10 or just stay 10 @jim_thompson5910

21. jim_thompson5910

anything positive will stay the same

22. jim_thompson5910

absolute value measures distance that number is from 0

23. jim_thompson5910

distance is never negative

24. anonymous

add em all up for the total again @jim_thompson5910

25. jim_thompson5910

yes

26. anonymous

how to find the variance @jim_thompson5910

27. jim_thompson5910

square everything in column 1 to get column 3

28. jim_thompson5910

0^2 = 0 0^2 = 0 (-10)^2 = 100 10^2 = 100 etc etc

29. jim_thompson5910

to get the MAD value, you add up everything in column 2 then divide by n = 8 to get the variance, you add up everything in column 3 then divide by n = 8 the standard deviation is equal to the square root of the variance

30. anonymous

did u get 490 for the total of the variance @jim_thompson5910

31. jim_thompson5910

divide 490 by 8 to get the variance

32. jim_thompson5910

33. anonymous

34. jim_thompson5910

I'm not sure what kind of answer they want here

35. jim_thompson5910

But the general rule is that the larger the standard deviation, the more spread out the scores are

36. anonymous

so who do you think should still win after all the work we have done... I still say Bryce @jim_thompson5910

37. jim_thompson5910

I'm not sure of that either. The two students both have good grades, but I guess Bryce has a higher max and Q3