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anonymous

  • one year ago

1234 Points: 2Question 2 Ten employees of a nursing home, having been given a course in cardiopulmonary resuscitation (CPR), scored 17, 20, 12, 14, 18, 23, 17, 19, 18, and 15 on a test administered after the completion of the course. Find the standard deviation and variance. Standard deviation = 2.97; Variance = 8.81 Standard deviation = 8.81; Variance = 8.81 Standard deviation = 8.81; Variance = 2.97 Standard deviation = 3.13; Variance = 9.59

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  1. anonymous
    • one year ago
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    @ZoMbAsH

  2. anonymous
    • one year ago
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    @welshfella @TheSmartOne

  3. welshfella
    • one year ago
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    hmm see if i remember this First find the mean of all the values by adding up all the values then dividing by 10

  4. anonymous
    • one year ago
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    k

  5. anonymous
    • one year ago
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    17.3

  6. welshfella
    • one year ago
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    the subtract the mean from each of the values so for 17 this will give 17-17.3 = -0.7 do this for all 10 values

  7. anonymous
    • one year ago
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    I'll be honest I have no idea :(

  8. anonymous
    • one year ago
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    why u choose 17?

  9. welshfella
    • one year ago
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    just as an example

  10. anonymous
    • one year ago
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    oh i see

  11. welshfella
    • one year ago
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    then you square each of the results and add them up. Finally divide the total by n

  12. welshfella
    • one year ago
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    |dw:1435251903888:dw|

  13. anonymous
    • one year ago
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    i dont no what the or the upside down h is

  14. welshfella
    • one year ago
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    where mu is the mean and Sigma means the total sum

  15. welshfella
    • one year ago
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    the n is total number of readinsg = 10

  16. welshfella
    • one year ago
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    thats the variance the standard deviation is the square root of the variabce

  17. welshfella
    • one year ago
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    * variance

  18. triciaal
    • one year ago
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    be careful with your computation

  19. welshfella
    • one year ago
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    I'm relying in memory but i think this is right

  20. welshfella
    • one year ago
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    maybe triciaal will confirm?

  21. anonymous
    • one year ago
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    so far i got -0.3, 2.7, -5.3, -3.3, 0.7, 5.7,-0.3, 1.7, 0.7, -2.3

  22. welshfella
    • one year ago
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    Ok so you square each one of these

  23. welshfella
    • one year ago
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    0.09, 7.29 etc

  24. anonymous
    • one year ago
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    ok

  25. welshfella
    • one year ago
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    now add them up then divide by 10

  26. anonymous
    • one year ago
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    0.09, 7.29, 28.09, 10.89, 0.49, 32.49, 0.09, 2.89, 0.49, 5, 29

  27. welshfella
    • one year ago
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    look s good

  28. triciaal
    • one year ago
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    @welshfella your process is fine, formula is correct, great job I was referring to the simple stuff 17 - 17.3 not = -0.7

  29. anonymous
    • one year ago
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    i got 9,807? wait did i do that wrong

  30. triciaal
    • one year ago
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    @jordanawest22 did you actually find the mean?

  31. anonymous
    • one year ago
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    i subtracted everythin from 17.3...ex)17-17.3....then i added them and divided by 10 and got , 8.807

  32. triciaal
    • one year ago
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    no after you subtract you square each then add before dividing by N

  33. anonymous
    • one year ago
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    what?, but the answer is up there??????

  34. welshfella
    • one year ago
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    i'm getting a bit confused myself!!!!! its value - mean right?

  35. anonymous
    • one year ago
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    thats what i did

  36. triciaal
    • one year ago
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    |dw:1435256442515:dw|

  37. welshfella
    • one year ago
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    so the first 1 is 17-17.3 = -0.3

  38. triciaal
    • one year ago
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    for the X each entry in the data here I have 1,2,3,4,5,

  39. anonymous
    • one year ago
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    i found the mean of the numberss in the question then i subtrated the mean by all of the units in the problem, i got mostly decimals...then i squared them all then added them then divided by 10

  40. welshfella
    • one year ago
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    yes thats correct - - i think its best to put it in a table as triciall has then you are less likely to make errors

  41. anonymous
    • one year ago
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    ok, i got 8.81 so that would be the variance right?

  42. welshfella
    • one year ago
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    i got 8.81 for the variance

  43. welshfella
    • one year ago
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    yes

  44. anonymous
    • one year ago
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    and to find the variance i do what now?

  45. welshfella
    • one year ago
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    8.81 is the variance std dev = square root of the variance

  46. triciaal
    • one year ago
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    |dw:1435256789840:dw|

  47. welshfella
    • one year ago
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    sqrt 8.81 = ?

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