VCE General & Further Maths Question Thread!

[Stick]

Bar charts are seperated. Each bar is separated, where as histograms are all touching each other, there is no break

While this isn't the most important difference between the two, this is an extremely important fact to remember for your Data Analysis SAC. Lots of people 'join up' their columns when drawing their bar graphs and examiners will dock a mark because:
1) you haven't understood a fundamental difference between two very different graphs
2) you're suggesting a relationship exists between the categories in the independent variable, which is not true.

[jimmy22]

Really basic thing i forgot how to do.
If you are applying a transformation, say x^2, what do you type in the calc to apply it to the whole column?

[jimmy22]

anyone?

[Kuchiki]

Assuming that you're using the TI-nspire... In Lists & Spreadsheet, after you've typed up a list of values in a column titled "x", go to another column and type "=x^2" in the grey box, press enter, and when it asks "Column or Variable", choose "Variable Reference". Press OK and it should come up with a list of x^2 values.

[vashappenin]

Ok I seriously am not digging chapter 7 from essentials, esp. 7E (attached)
Can someone please help with 1c? I thought I was doing it right, but my answer is completely off the answer in the textbook, which is 692,000
And also 2a please! How can I do least squares regression if there's 4 different no. of purchases?

And one more thing that's unrelated to the questions above but still bugs the crap out of me, how do I 'clear history' on lists and spreadsheets? Like I'll be doing a question and naming column A 'x' for example, and then when I open a new lists and spreadsheets, it's still defined as the previous x. My teacher said to just 'clear a-z' in the calculator page, but is there no other way?

Thanks

[Stick]

1C: Did you standardise the years in the x-axis? It says to make 1992 the number 1 and go onwards from there. Also, make sure that you determine the right number for the year 2008. You might be one number off, so quickly make a little list.

2A: Work through the the quarters (in order) of year 1, then year 2, then year 3. Don't do something silly like taking the average.

Calculator: Not sure what calculator you use, but I just stopped defining the lists because I had a similar issue. Why do you have to label them?

[vashappenin]

1C: Did you standardise the years in the x-axis? It says to make 1992 the number 1 and go onwards from there. Also, make sure that you determine the right number for the year 2008. You might be one number off, so quickly make a little list.

Yep I did this, but my answer was still off :S

2A: Work through the the quarters (in order) of year 1, then year 2, then year 3. Don't do something silly like taking the average.

I'm not sure what you mean by this :S

Calculator: Not sure what calculator you use, but I just stopped defining the lists because I had a similar issue. Why do you have to label them?

I use the grey CAS. So you don't have to label them? What do you do then, if you need to draw a graph using the data? Don't you have to name them then?

Thanks for the help

[Stick]

Yep I did this, but my answer was still off :S
I'm not sure what you mean by this :S
I use the grey CAS. So you don't have to label them? What do you do then, if you need to draw a graph using the data? Don't you have to name them then?

Thanks for the help

1C: Hmm... I'm not sure. Perhaps check your working out? :S

2A: Year 1 Q1, Year 1 Q2, Year 1 Q3, Year 1 Q4, Year 2 Q1...

Calculator: I was able to draw graphs without labelling the axes. I guess I can't help there. :/

[Zealous]

And one more thing that's unrelated to the questions above but still bugs the crap out of me, how do I 'clear history' on lists and spreadsheets? Like I'll be doing a question and naming column A 'x' for example, and then when I open a new lists and spreadsheets, it's still defined as the previous x. My teacher said to just 'clear a-z' in the calculator page, but is there no other way?
Thanks

I think you may have to start a new document, I've been bugged by it also... I just try keeping my label's as unique as possible so I don't come across it twice, then I start a new document once I'm done.

1c) I got a regression of

number of students = 10.09 x year + 520.4

When standardised, 2008 is the 17th year.

And I got an answer of 691.93.

So maybe you've just messed up the decimal places somewhere? are you using exact values in the lists and spreadsheets?

[jimmy22]

Hi,
I have a question where there is an upward cyclic graph.
For the first part i had to perform a 3 point moving median smoothing.

In the second part it says, 'It was suggested a 4-point moving median smoothing would be more appropriate. State a reason as to why this may be true.'

What might be an appropriate answer for this?

[Stick]

Smoothing is more likely to reflect the cyclic trend in the data.

[jimmy22]

Thanks,
Also would it be better to say something has an upward trend or positive trend?

There is a question that is 2 marks and asks us to comment on the features of the time series plot. Would saying that it has a positive/upward cyclic trend be enough for the 2 marks?

[jimmy22]

Also, this may be a silly question but does the residual value have units? (the same units as the actual value).

[brenden]

In time series, say upward. In describing linearity from a stem plot or something, use positive.
Sounds like enough for the marks, from memory. (Can't believe how much Further has gone out of my head, I only just realised)

I need clarification on your last question.

[jimmy22]

Thanks,
So if it says 'state the residual for the national car sales in quarter 3.'

I have figured out the residual = 4300,
do i say residual = 4300 car sales?