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anonymous

  • one year ago

Help please

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  1. anonymous
    • one year ago
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    A student is assessing the correlation between the average number of hours of internet browsing and average score on a math test for the students of a class. The table below shows the data: Part A: Is there any correlation between the average number of hours of internet browsing and average score on the math test for the students of the class? Justify your answer. Part B: Write a function which best fits the data. Part C: What does the slope and y-intercept of the plot indicate?

  2. anonymous
    • one year ago
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    @jim_thompson5910

  3. jim_thompson5910
    • one year ago
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    what spreadsheet program do you have?

  4. anonymous
    • one year ago
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    Ok so I made my own graph for part A and I found that it has a negative correlation, right?

  5. anonymous
    • one year ago
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    I used geogebra for this graph i just attached

  6. jim_thompson5910
    • one year ago
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    geogebra is a good choice

  7. jim_thompson5910
    • one year ago
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    you can also use geogebra for spreadsheet work

  8. anonymous
    • one year ago
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    Yea, so that would be negative correlation right?

  9. jim_thompson5910
    • one year ago
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    at the top go to view --> spreadsheet

  10. jim_thompson5910
    • one year ago
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    we'll find out

  11. jim_thompson5910
    • one year ago
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    oh wait, you already have the points plotted

  12. anonymous
    • one year ago
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    Ok i did that

  13. anonymous
    • one year ago
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    Now what?

  14. jim_thompson5910
    • one year ago
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    in the input bar below, type CorrelationCoefficient[ then enter the list of points surrounded by curly braces

  15. jim_thompson5910
    • one year ago
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    So if you had points A through J, then you would have CorrelationCoefficient[{A,B,C,D,E,F,G,H,I,J}]

  16. anonymous
    • one year ago
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  17. anonymous
    • one year ago
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    When I press enter it erases

  18. jim_thompson5910
    • one year ago
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    where is the algebra tab? can I see that?

  19. anonymous
    • one year ago
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    algebra tab?

  20. jim_thompson5910
    • one year ago
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    at the top go to View ---> algebra

  21. jim_thompson5910
    • one year ago
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    I'm curious to see what the point labels are

  22. anonymous
    • one year ago
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  23. jim_thompson5910
    • one year ago
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    thx

  24. jim_thompson5910
    • one year ago
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    for some reason, you did (0.95) twice

  25. jim_thompson5910
    • one year ago
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    delete point A then do CorrelationCoefficient[{B,C,D,E,F,G,H,I,J,K}]

  26. jim_thompson5910
    • one year ago
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    oh I see what happened

  27. jim_thompson5910
    • one year ago
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    do you see the lower case letters a though g? how they're all -1 those are the results of you typing in CorrelationCoefficient[{A,B,C,D,E,F,G,H,I,J}] so the correlation coefficient is -1

  28. jim_thompson5910
    • one year ago
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    now that I think about it, it might be better to do this sort of command in the CAS

  29. anonymous
    • one year ago
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    oh ok so it is negative correlation

  30. jim_thompson5910
    • one year ago
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    r = -1 means we have perfect negative correlation all of the points lie on the same line

  31. anonymous
    • one year ago
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    but hmm not sure why i put 0.95 twice

  32. jim_thompson5910
    • one year ago
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    the line has some negative slope

  33. anonymous
    • one year ago
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    oh ok wait brb

  34. anonymous
    • one year ago
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    So part A is negative correlation

  35. anonymous
    • one year ago
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    Part B....

  36. jim_thompson5910
    • one year ago
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    in the input bar, type FitLine[{A,B,C,D,E,F,G,H,I,J}] and an equation of the line will pop up in the algebra tab

  37. jim_thompson5910
    • one year ago
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    or you can pick any two points and find the slope, then use y = mx+b

  38. anonymous
    • one year ago
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    It never works when i go to the input bar

  39. jim_thompson5910
    • one year ago
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    ok go to the CAS then view --> CAS

  40. jim_thompson5910
    • one year ago
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    type FitLine[{A,B,C,D,E,F,G,H,I,J}] into the CAS

  41. anonymous
    • one year ago
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  42. jim_thompson5910
    • one year ago
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  43. anonymous
    • one year ago
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    Oh ok but your last three points are wrong

  44. jim_thompson5910
    • one year ago
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    right, they skipped 88 for some reason

  45. anonymous
    • one year ago
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    It should be (3.5,87) and (4,86) and (4.5,85)

  46. anonymous
    • one year ago
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    yea

  47. anonymous
    • one year ago
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    so now what does the slope say once you fix that

  48. jim_thompson5910
    • one year ago
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  49. jim_thompson5910
    • one year ago
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    the correlation coefficient r is no longer -1 exactly, but it's still pretty close

  50. anonymous
    • one year ago
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    I went to mathway and it said this,....

  51. jim_thompson5910
    • one year ago
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    that only works if you consider those two points only

  52. jim_thompson5910
    • one year ago
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    but we have to consider all 10 points

  53. jim_thompson5910
    • one year ago
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    which is what the FitLine function does

  54. anonymous
    • one year ago
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    Oh ok

  55. anonymous
    • one year ago
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    And lastly, part C

  56. anonymous
    • one year ago
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    Well the slope is -2.25 and the y intercept is 95.27... but what does it indicate?

  57. jim_thompson5910
    • one year ago
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    what do x and y represent?

  58. anonymous
    • one year ago
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    I dont know

  59. anonymous
    • one year ago
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    @jim_thompson5910

  60. jim_thompson5910
    • one year ago
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    look back at the table given in the problem

  61. anonymous
    • one year ago
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    Do you want the coordinates?

  62. jim_thompson5910
    • one year ago
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    they define in words what x and y are

  63. jim_thompson5910
    • one year ago
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    x = number of hours browsing the internet y = ???

  64. anonymous
    • one year ago
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    Oh y is the score of the math test

  65. jim_thompson5910
    • one year ago
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    yeah

  66. jim_thompson5910
    • one year ago
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    what does the y intercept represent?

  67. anonymous
    • one year ago
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    I really dont know

  68. jim_thompson5910
    • one year ago
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    it's where the x coordinate is 0 right? basically where the graph crosses the y axis

  69. jim_thompson5910
    • one year ago
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    the y-intercept of the regression line is where the predicted score would be if you spend no time on the internet ie, if you spend no time on the internet, then it is predicted you get a score of 95.27

  70. jim_thompson5910
    • one year ago
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    the slope tells us how the score changes as x changes each time the number of hours browsing the internet goes up by 1, the predicted score goes down by about -2.25

  71. anonymous
    • one year ago
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    Thank you! Thank you! Thank you!!!!!

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