# logarithms question help

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#1
https://activeteach-prod.resource.pe...b_p1_ex14h.pdf

For question 6c, wouldn't the y-intercept (logA) be 3.69? Where did they get 3.76 from?
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1 month ago
#2
(Original post by Zerefina)
https://activeteach-prod.resource.pe...b_p1_ex14h.pdf

For question 6c, wouldn't the y-intercept (logA) be 3.69? Where did they get 3.76 from?
The points are not all exactly on a straight line. They have taken the intercept from an attempted line of best fit through (or past) all the points rather than from the single point (0, 3.69).
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#3
(Original post by old_engineer)
The points are not all exactly on a straight line. They have taken the intercept from an attempted line of best fit through (or past) all the points rather than from the single point (0, 3.69).
I see, would it be wrong if I used the point (0, 3.69) rather than from the straight line? If I used 3.69, A would be 4900, which is 900 less than the official answer. Should I be using the straight line from now on instead of the single point?
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1 month ago
#4
(Original post by Zerefina)
I see, would it be wrong if I used the point (0, 3.69) rather than from the straight line? If I used 3.69, A would be 4900, which is 900 less than the official answer. Should I be using the straight line from now on instead of the single point?
Linear regression gives an intercept of 3.76.

Strangely the solution bank says "reading the intercept from the graph" and they don't seem to have done this.
1
1 month ago
#5
(Original post by Zerefina)
I see, would it be wrong if I used the point (0, 3.69) rather than from the straight line? If I used 3.69, A would be 4900, which is 900 less than the official answer. Should I be using the straight line from now on instead of the single point?
It's usually best to use the line of best fit rather than a single point.
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#6
(Original post by Plücker)
Linear regression gives an intercept of 3.76.

Strangely the solution bank says "reading the intercept from the graph" and they don't seem to have done this.
My textbook also says "reading the intercept from the graph" in the examples given. I haven't done linear interpolation in a very long while D:
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#7
(Original post by old_engineer)
It's usually best to use the line of best fit rather than a single point.
Ok, thank you
1
1 month ago
#8
(Original post by Zerefina)
My textbook also says "reading the intercept from the graph" in the examples given. I haven't done linear interpolation in a very long while D:
Oh, that was your textbook, I thought it was the solution bank. This would be linear regression rather than interpolation. Finding the line of best fit by linear regression is no longer in the syllabus. As old_engineer says, using the line of best fit is best in these cases as you're using all the data rather than just one point.
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#9
(Original post by Plücker)
Oh, that was your textbook, I thought it was the solution bank. This would be linear regression rather than interpolation. Finding the line of best fit by linear regression is no longer in the syllabus. As old_engineer says, using the line of best fit is best in these cases as you're using all the data rather than just one point.
It said that in both the textbook and the solution bank. I vaguely remember learning something about linear regression but not much about it so I was slightly confused. Thank you for the help
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