VCE General & Further Maths Question Thread!

[Peanut Butter]

For a residual plot, does the x-axis scale remain the same and the y scale changes? thanks

Yes

The x-axis remains the original x values but the y-axis becomes the residual values

[Escobar]

for the exams, are we expected to know how to plot residuals on our CAS?
also, would we ever need to smooth a large number of results?

[Adiamond]

for the exams, are we expected to know how to plot residuals on our CAS?
also, would we ever need to smooth a large number of results?

I've seen some residual plots in the multiple choice, most can be done through elimination but if you have some extra time at the end it might be useful to plot the residual on your CAS, as for smoothing large numbers of results, you won't have to.
But it's definitely good to know how to do 4-moving median smoothing with centring and maybe even practice with 6-moving median/mean just to get a good feel for it.

-Someone please correct me if i'm wrong for the smoothing thing, i've not done too many exams.

[_fruitcake_]

I've seen some residual plots in the multiple choice, most can be done through elimination but if you have some extra time at the end it might be useful to plot the residual on your CAS, as for smoothing large numbers of results, you won't have to.
But it's definitely good to know how to do 4-moving median smoothing with centring and maybe even practice with 6-moving median/mean just to get a good feel for it.

-Someone please correct me if i'm wrong for the smoothing thing, i've not done too many exams.

Yeah its usually from 2-6, the most common one i have seen is 5

[Peanut Butter]

for the exams, are we expected to know how to plot residuals on our CAS?

It's not necessary, however I would recommend learning how to do it (it's pretty simple)! Usually on an exam 2 they would only require you to plot one (or two) residual points and they would give the rest to you - just because plotting a whole residual graph takes a lot of time.

Learning to do it on your CAS could come in handy for a multiple choice question or even to just double check your work

[Escobar]

thanks guys 
also
do we need to label points with coordinates when we plot them?

[Peanut Butter]

thanks guys 
also
do we need to label points with coordinates when we plot them?

I'm not entirely sure what the rules are... but my teacher said to always label your coordinates so that the examiners are guaranteed to know where you are plotting

[Peanut Butter]

Are we expected to know blending for graphs and relations?

[_fruitcake_]

Are we expected to know blending for graphs and relations?

I have no clue what blending is and i have done every exam.. so probably not

[Peanut Butter]

Thanks!!

Also, for core, if a value is on the upper/lower fence is it considered an outlier? Or are outliers only points beyond the fences?

[_fruitcake_]

Thanks!!

Also, for core, if a value is on the upper/lower fence is it considered an outlier? Or are outliers only points beyond the fences?

fences? If they are a dot on the scale of a boxplot its an outlier. If you need to draw a boxplot and want to know which one is an outlier u can work it out with Q1-1.5xIQR and Q3+1.5xIQR. I dont get what u mean by fences.

[Peanut Butter]

fences? If they are a dot on the scale of a boxplot its an outlier. If you need to draw a boxplot and want to know which one is an outlier u can work it out with Q1-1.5xIQR and Q3+1.5xIQR. I dont get what u mean by fences.

At my school we call fences the exact point of (Q1 - 1.5IQR) and (Q3 + 1.5IQR).

So what I mean... those points mentioned above [(Q1 - 1.5IQR) and (Q3 + 1.5IQR)], if something was equal to that value would it be an outlier or not?

Example: If Q1 - 1.5IQR = 4 and I have a data value that was 4 - is this value an outlier? or not?

[BakedDwarf]

At my school we call fences the exact point of (Q1 - 1.5IQR) and (Q3 + 1.5IQR).

So what I mean... those points mentioned above [(Q1 - 1.5IQR) and (Q3 + 1.5IQR)], if something was equal to that value would it be an outlier or not?

Example: If Q1 - 1.5IQR = 4 and I have a data value that was 4 - is this value an outlier? or not?

An outlier must be below the lower fence or above the upper fence.

In response to your question, 4 is not an outlier because it is not less than the lower fence (4 cannot be below 4, can it?)

[_fruitcake_]

At my school we call fences the exact point of (Q1 - 1.5IQR) and (Q3 + 1.5IQR).

So what I mean... those points mentioned above [(Q1 - 1.5IQR) and (Q3 + 1.5IQR)], if something was equal to that value would it be an outlier or not?

Example: If Q1 - 1.5IQR = 4 and I have a data value that was 4 - is this value an outlier? or not?

My book says it is an outlier - the equation is Q1-1.5xIQR (<=)x(>=)Q3+1.5xIQR, the (<=) means that it could be equal to, so it would be an outlier.

But other people are saying it isnt, so before i sue my book for trying to ruin my chance of a 50, i will wait for others to say stuff

[BakedDwarf]

My book says it is an outlier - the equation is Q1-1.5xIQR (<=)x(>=)Q3+1.5xIQR, the (<=) means that it could be equal to, so it would be an outlier.

But other people are saying it isnt, so before i sue my book for trying to ruin my chance of a 50, i will wait for others to say stuff

Well, according to maths quest, what i said above is correct because an outlier lies outside the interval of the attached picture.

What book are you using?