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cnu115

  • one year ago

On an exam, a class ended with a mean raw score of 80 with standard deviation of 10. The distribution of grades in the class was approximately normal. If the teacher wants to give "A" to the top 25th percentile (top 25%) of the class, what is the lowest raw score we could get and still get an "A" on the exam?

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  1. dan815
    • one year ago
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    |dw:1373527655365:dw|

  2. cnu115
    • one year ago
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    standard deviation of 10

  3. dan815
    • one year ago
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    lol i mean how many deviation points wud u have to travel, to be left with only 25% area on the right side

  4. dan815
    • one year ago
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    look up the probability distribution graph numbers

  5. cnu115
    • one year ago
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    Sorry sir, I could not follow you. Could you please explain

  6. dan815
    • one year ago
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    look at that and see at what standard deviation you have to be to be left with only 25% area on the right side

  7. dan815
    • one year ago
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    |dw:1373530622874:dw|

  8. cnu115
    • one year ago
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    Is it 21% with 0.8 standard deviation?

  9. cnu115
    • one year ago
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    It is only one standard deviation point above the mean is to be covered. Isn't it? Other please explain

  10. dan815
    • one year ago
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    |dw:1373533594767:dw|

  11. dan815
    • one year ago
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    how much more deviation does she have to go to cover upto 75%

  12. dan815
    • one year ago
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    look at that chart and figure it out

  13. dan815
    • one year ago
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    |dw:1373533703309:dw|

  14. dan815
    • one year ago
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    its somewhre inbetween 0.5 and 1

  15. dan815
    • one year ago
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    id say around 0.75

  16. dan815
    • one year ago
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    so 0.75 of 10 = ? 7.5 marks

  17. dan815
    • one year ago
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    then 87.5 should be the marks she needs to set it at

  18. dan815
    • one year ago
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    im just estimating values here, im sure u got some formulas to calculate the exact z values and stuff

  19. dan815
    • one year ago
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    |dw:1373533813410:dw|

  20. cnu115
    • one year ago
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    This Z values I am not aware sir. I am just browsing about this

  21. dan815
    • one year ago
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    this will give u more accurate vlaue

  22. dan815
    • one year ago
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    |dw:1373533861018:dw|

  23. dan815
    • one year ago
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    |dw:1373533886859:dw|

  24. dan815
    • one year ago
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    |dw:1373533895795:dw|

  25. dan815
    • one year ago
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    |dw:1373533946389:dw|

  26. dan815
    • one year ago
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    |dw:1373533966949:dw|

  27. dan815
    • one year ago
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    |dw:1373533987799:dw|

  28. cnu115
    • one year ago
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    |dw:1373534025223:dw|

  29. cnu115
    • one year ago
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    what is this equation you have used

  30. dan815
    • one year ago
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    5.6/15

  31. dan815
    • one year ago
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    because

  32. dan815
    • one year ago
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    look at the chart

  33. dan815
    • one year ago
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    at 0.5 deviation on right how much percent have you covered?

  34. cnu115
    • one year ago
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    and how did you get 0.37

  35. dan815
    • one year ago
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    do you know the answer already

  36. cnu115
    • one year ago
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    ????? 5*6/15=0.37 ????

  37. dan815
    • one year ago
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    whats the answer supposed to be

  38. dan815
    • one year ago
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    its 5.6 not 5 * 6

  39. dan815
    • one year ago
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    i cant help you if u arent answering my questions

  40. cnu115
    • one year ago
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    No. Idon't know the answer

  41. dan815
    • one year ago
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    then dont bother with stuff

  42. dan815
    • one year ago
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    first understand the graph

  43. cnu115
    • one year ago
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    I want to know more about this Z score

  44. cnu115
    • one year ago
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    Ok sir

  45. dan815
    • one year ago
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    the graph is pretty self explanatory and questions about it?

  46. dan815
    • one year ago
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    any questions?

  47. cnu115
    • one year ago
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    just a second sir,

  48. cnu115
    • one year ago
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    Now it is clear. But one question. May I ask

  49. cnu115
    • one year ago
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    Why did you divide by 15. It is only 14 parts. Right

  50. cnu115
    • one year ago
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    Sorry. Now I have fully understood.

  51. cnu115
    • one year ago
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    It is not the 14 parts. It is the area of that part.

  52. cnu115
    • one year ago
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    Thank you very much explaining in detailed manner

  53. cnu115
    • one year ago
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    Thanks for your patience and analysing for a lehman.

  54. Musadiq
    • one year ago
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    Mean 80 standard deviation 10 z=-0.67 X=73.3

  55. Musadiq
    • one year ago
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    mine answer is 73.3 marks min to get A

  56. Musadiq
    • one year ago
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    you have to take Z value -0.67

  57. dan815
    • one year ago
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    musadiq no try taking 0.67 Z

  58. Musadiq
    • one year ago
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    well table value is 0.67 that's lies at left side !

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