anonymous
  • anonymous
Help please
Mathematics
  • Stacey Warren - Expert brainly.com
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schrodinger
  • schrodinger
I got my questions answered at brainly.com in under 10 minutes. Go to brainly.com now for free help!
anonymous
  • anonymous
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?
anonymous
  • anonymous
@jim_thompson5910
jim_thompson5910
  • jim_thompson5910
what spreadsheet program do you have?

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anonymous
  • anonymous
Ok so I made my own graph for part A and I found that it has a negative correlation, right?
anonymous
  • anonymous
I used geogebra for this graph i just attached
jim_thompson5910
  • jim_thompson5910
geogebra is a good choice
jim_thompson5910
  • jim_thompson5910
you can also use geogebra for spreadsheet work
anonymous
  • anonymous
Yea, so that would be negative correlation right?
jim_thompson5910
  • jim_thompson5910
at the top go to view --> spreadsheet
jim_thompson5910
  • jim_thompson5910
we'll find out
jim_thompson5910
  • jim_thompson5910
oh wait, you already have the points plotted
anonymous
  • anonymous
Ok i did that
anonymous
  • anonymous
Now what?
jim_thompson5910
  • jim_thompson5910
in the input bar below, type CorrelationCoefficient[ then enter the list of points surrounded by curly braces
jim_thompson5910
  • jim_thompson5910
So if you had points A through J, then you would have CorrelationCoefficient[{A,B,C,D,E,F,G,H,I,J}]
anonymous
  • anonymous
anonymous
  • anonymous
When I press enter it erases
jim_thompson5910
  • jim_thompson5910
where is the algebra tab? can I see that?
anonymous
  • anonymous
algebra tab?
jim_thompson5910
  • jim_thompson5910
at the top go to View ---> algebra
jim_thompson5910
  • jim_thompson5910
I'm curious to see what the point labels are
anonymous
  • anonymous
jim_thompson5910
  • jim_thompson5910
thx
jim_thompson5910
  • jim_thompson5910
for some reason, you did (0.95) twice
jim_thompson5910
  • jim_thompson5910
delete point A then do CorrelationCoefficient[{B,C,D,E,F,G,H,I,J,K}]
jim_thompson5910
  • jim_thompson5910
oh I see what happened
jim_thompson5910
  • jim_thompson5910
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
jim_thompson5910
  • jim_thompson5910
now that I think about it, it might be better to do this sort of command in the CAS
anonymous
  • anonymous
oh ok so it is negative correlation
jim_thompson5910
  • jim_thompson5910
r = -1 means we have perfect negative correlation all of the points lie on the same line
anonymous
  • anonymous
but hmm not sure why i put 0.95 twice
jim_thompson5910
  • jim_thompson5910
the line has some negative slope
anonymous
  • anonymous
oh ok wait brb
anonymous
  • anonymous
So part A is negative correlation
anonymous
  • anonymous
Part B....
jim_thompson5910
  • jim_thompson5910
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
jim_thompson5910
  • jim_thompson5910
or you can pick any two points and find the slope, then use y = mx+b
anonymous
  • anonymous
It never works when i go to the input bar
jim_thompson5910
  • jim_thompson5910
ok go to the CAS then view --> CAS
jim_thompson5910
  • jim_thompson5910
type FitLine[{A,B,C,D,E,F,G,H,I,J}] into the CAS
anonymous
  • anonymous
jim_thompson5910
  • jim_thompson5910
1 Attachment
anonymous
  • anonymous
Oh ok but your last three points are wrong
jim_thompson5910
  • jim_thompson5910
right, they skipped 88 for some reason
anonymous
  • anonymous
It should be (3.5,87) and (4,86) and (4.5,85)
anonymous
  • anonymous
yea
anonymous
  • anonymous
so now what does the slope say once you fix that
jim_thompson5910
  • jim_thompson5910
1 Attachment
jim_thompson5910
  • jim_thompson5910
the correlation coefficient r is no longer -1 exactly, but it's still pretty close
anonymous
  • anonymous
I went to mathway and it said this,....
jim_thompson5910
  • jim_thompson5910
that only works if you consider those two points only
jim_thompson5910
  • jim_thompson5910
but we have to consider all 10 points
jim_thompson5910
  • jim_thompson5910
which is what the FitLine function does
anonymous
  • anonymous
Oh ok
anonymous
  • anonymous
And lastly, part C
anonymous
  • anonymous
Well the slope is -2.25 and the y intercept is 95.27... but what does it indicate?
jim_thompson5910
  • jim_thompson5910
what do x and y represent?
anonymous
  • anonymous
I dont know
anonymous
  • anonymous
@jim_thompson5910
jim_thompson5910
  • jim_thompson5910
look back at the table given in the problem
anonymous
  • anonymous
Do you want the coordinates?
jim_thompson5910
  • jim_thompson5910
they define in words what x and y are
jim_thompson5910
  • jim_thompson5910
x = number of hours browsing the internet y = ???
anonymous
  • anonymous
Oh y is the score of the math test
jim_thompson5910
  • jim_thompson5910
yeah
jim_thompson5910
  • jim_thompson5910
what does the y intercept represent?
anonymous
  • anonymous
I really dont know
jim_thompson5910
  • jim_thompson5910
it's where the x coordinate is 0 right? basically where the graph crosses the y axis
jim_thompson5910
  • jim_thompson5910
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
jim_thompson5910
  • jim_thompson5910
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
anonymous
  • anonymous
Thank you! Thank you! Thank you!!!!!

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