VCE General & Further Maths Question Thread!

[Sirius]

For the second pic, how do i do 2b

I hope you understand 

[TheCommando]

Question 10

Solve (19282.65 = R⁸ * 18000)
You get R = 1.00864 and R = 1 + (r/4)/100

And solve this and you get r = 3.456

Why do u do 1+(r/4)/100=1.00864

I hope you understand 

Thank you sirius black


Mod Edit: Double post merged.... again

[Sirius]

Why do u do 1+(r/4)/100=1.00864

Sorry for the late reply but as R is equal to 1+ (interest rate/compounding periods)/100.
To find the interest rate I used the R  value (1.00864) and solved the equation.
Let me know if you don't catch on. Sorry if this caused any confusion. There may be more than one way you can solve this!.

[plato]

Hey,
I am confused about using rounded and unrounded answers in Further. In the exam, what are we expected to use?
For example, if part a asked for an answer to 2 dp
and then for part b you need to use part a's answer, do we use the rounded or unrounded answer??

thanks

At a meeting with assessors this year, we were told that the correct answer will be the same either way. But they suggest the previous answer, rounded as required in that question, is the better option to use.

[BlinkieBill]

Hey, for the Core Data Analysis section, I was wondering whether or not a distribution has to be perfectly symmetrical to describe it as symmetrical in the exam?
And if something is reasonably symmetrical, but not perfectly, could you say it was slightly positively/negatively skewed?
Thanks.

[TFAnime123]

Hey all,
Can someone help me with this question?

The seasonal indices for the number of bathing suits sold at a surf shop are given in the
table.
Quarter:            Summer  Autumn     Winter     Spring
Seasonal index: 1.8             0.4           0.3          1.5

12. To correct for seasonality, the actual number of bathing suits sold in Autumn
should be:
A) reduced by 60%
B) reduced by 40%
C) increased by 40%
D) increased by 60%
E) increased by 250%

I'm not too sure if the textbook has a typo, but I seem to get 'increased by 150%'

[AngelWings]

Hey, for the Core Data Analysis section, I was wondering whether or not a distribution has to be perfectly symmetrical to describe it as symmetrical in the exam?
And if something is reasonably symmetrical, but not perfectly, could you say it was slightly positively/negatively skewed?
Thanks.

I think I remember that it doesn't necessarily have to be perfectly symmetrical to say that it is, although it is best to err on the side of caution and say that it is slightly positively/ negatively skewed as the case may be. Generally past papers have been reasonably clear as to whether they're looking for slightly skewed or symmetrical.

Hey all,
Can someone help me with this question?

The seasonal indices for the number of bathing suits sold at a surf shop are given in the
table.
Quarter:            Summer  Autumn     Winter     Spring
Seasonal index: 1.8             0.4           0.3          1.5

12. To correct for seasonality, the actual number of bathing suits sold in Autumn
should be:
A) reduced by 60%
B) reduced by 40%
C) increased by 40%
D) increased by 60%
E) increased by 250%

I'm not too sure if the textbook has a typo, but I seem to get 'increased by 150%'

It looks like you're right in this case and that's just a typo. (Then again, I just glimpsed this for a second.)
I don't have the time to properly link you to my previous post way back when I did a similar exam question (VCAA Exam 1 2011 Core Q11), but search through my many posts to find it and it'll show you a similar method to check your answer.

[TheCommando]

Hey guys, how do i do the lastt question
I dont know the concept

[AngelWings]

Hey guys, how do i do the lastt question
I dont know the concept

This requires you to know how the mean and standard deviation are calculated.
Do you remember how to...

...calculate a mean?

You can do so by taking the sum of all the data and then dividing by the number of data pieces (samples).

...calculate a standard deviation?

To calculate a standard deviation, you must take the variance of the data (so the data variation, or how far one single data point is away from the mean) and then take its square root. You can search the true formula, involving the sum of squares if you'd like the whole statistics story there or the entire formula if you want, but all you need to really know is that standard deviation is the spread of data and that's where the normal distribution comes from (it assumes your data is normal or close to it).

Working out + Answer

From this, you can tell that by changing the points directly, you'll definitely be influencing the mean - and, if you read the question correctly, say that the stakes are reduced by 5 cm - so you know that the mean will likely also go down 5 cm. This cuts out options B and E automatically.

Then we need to know if the standard deviation will change. The spread will not move if the points are directly changed. That's because it is according to the position of the mean, rather than the points themselves; all the points will change, so the mean changes, but how far each point from the mean is, will not. (PM me if this isn't an adequate explanation for you... I'll be back regularly in about a week - after my exams are over.)

Summary: mean - will change, standard deviation - will not change.
The correct option should be option C.

[TheCommando]

This requires you to know how the mean and standard deviation are calculated.
Do you remember how to...

...calculate a mean?

You can do so by taking the sum of all the data and then dividing by the number of data pieces (samples).

...calculate a standard deviation?

To calculate a standard deviation, you must take the variance of the data (so the data variation, or how far one single data point is away from the mean) and then take its square root. You can search the true formula, involving the sum of squares if you'd like the whole statistics story there or the entire formula if you want, but all you need to really know is that standard deviation is the spread of data and that's where the normal distribution comes from (it assumes your data is normal or close to it).

Working out + Answer

From this, you can tell that by changing the points directly, you'll definitely be influencing the mean - and, if you read the question correctly, say that the stakes are reduced by 5 cm - so you know that the mean will likely also go down 5 cm. This cuts out options B and E automatically.

Then we need to know if the standard deviation will change. The spread will not move if the points are directly changed. That's because it is according to the position of the mean, rather than the points themselves; all the points will change, so the mean changes, but how far each point from the mean is, will not. (PM me if this isn't an adequate explanation for you... I'll be back regularly in about a week - after my exams are over.)

Summary: mean - will change, standard deviation - will not change.
The correct option should be option C.

I dont get why standard deviation doesnt change, i just accept that it just doesnt.

The spread will not move if the points are directly changed. That's because it is according to the position of the mean,
Not to sure about that, is that because the ratio of the other points to the mean stay the same?

Not to sure what sd is :/
Thank you so much!

[pmmenotes]

Math sac tomorrow and im kind of freaking out. I have done the chapters (8,9) and the practice sac and have made my notes for chap 9 but not 8 yet. Has anyone done the financial math sac yet and if so how was it? and tips

[Sirius]

Math sac tomorrow and im kind of freaking out. I have done the chapters (8,9) and the practice sac and have made my notes for chap 9 but not 8 yet. Has anyone done the financial math sac yet and if so how was it? and tips

Hey Pmmenotes,
I completed my financial math Sac recently. I personally used my textbook rather than my notes as this is what I was confident with. But you can equally use your own notes. Whatever works best for you! 
Some Tips:
- Include a lot of example questions in your notes: As you are making your notes I would highly recommend chucking in questions you found difficult so that you can refer back to them if you are stuck. For my sac I came to a question that I was completely stuck on and did not know how to solve. In vain hope I was flipping through my textbook and to my utter surprise I found a very similar worked example question (coincidence? Maybe ). Moral of the story: Include a fair amount of examples in your notes.
-Know your equations/formulas: In financial maths there are a heaps of different equations for different loans and investments and whatnot (depreciation, annuities, perpetuity etc.), therefore it is highly important to know which one of these the question is asking you to apply. Whether the question is asking for a reducing balance loan or a interest only loan know these equations and when to use them. It is really not that difficult, you will have these in your notes anyways. Just try not to confuse them as much as I do!
-[During the SAC] Read the question twice and highlight important parts: Sometimes what I tend to do is answer the question partly (especially when it has two or more sections) or misread it and supply my answer to 3 decimal places when it clearly asked to 2 d.p. You can use other techniques to overcome this problem such as check all answers at the end of the SAC etc. This is just a general tip yet I always fall for it. 

Last thing, walk into that room with confidence and please don't be scared. Being calm and collected would lead to less errors in the SAC. Therefore be confident in your abilities and give it your best shot tomorrow and you will do great .
Hope this has helped you a little. And good luck for your sac

[AngelWings]

I dont get why standard deviation doesnt change, i just accept that it just doesnt.

The spread will not move if the points are directly changed. That's because it is according to the position of the mean,
Not to sure about that, is that because the ratio of the other points to the mean stay the same?

Not to sure what sd is :/
Thank you so much!

It takes a lot more explaining than the time I have now, but I'd be happy to come back at the end of next week to discuss this if you wish. I currently am on exams (2 down, 3 more to go) and right now on a study break, so I'll come back to this soon. Pop me a PM to remind me if I forget, please. Sorry about the delay!
However, you can kind of say that the ratio remains the same. I guess that's one way you can think of it.

Math sac tomorrow and im kind of freaking out. I have done the chapters (8,9) and the practice sac and have made my notes for chap 9 but not 8 yet. Has anyone done the financial math sac yet and if so how was it? and tips

Sorry I didn't see this earlier; had a killer exam this morning! Sirius has a great answer, but I thought I'd add my two cents, despite not doing financial maths since Year 9 maths (it wasn't part of Core until last year).
Each school has a different SAC, although they should remain close to the exam, so ideally, you should've been doing practise questions from either VCAA or a company paper and writing your cheat sheet up in a way you understand it most.
For financial maths, I would highly recommend that you try some of the old Sequences & Series (old module 1) and see if you can do those. They are pretty similar in structure and format. At a glance, it also seems to be mostly a matter of deriving the correct equation, knowing the patterns and inputting the correct function into your calculator.
Hopefully that helps for your next SAC or the exams.

[plato]

-Know your equations/formulas: In financial maths there are a heaps of different equations for different loans and investments and whatnot (depreciation, annuities, perpetuity etc.), therefore it is highly important to know which one of these the question is asking you to apply. Whether the question is asking for a reducing balance loan or a interest only loan know these equations and when to use them. It is really not that difficult, you will have these in your notes anyways. Just try not to confuse them as much as I do!

I cannot agree that there are heaps of equations and formulas in the current Further financial curriculum. There is only the compound interest formula along with basic percentage calculations to solve simple loan, investment and depreciation problems. You do not need any other financial formula.
I think the main focus is on understanding the growth or decay of the balances of the types loan, investment and depreciation defined in the study design. Recurrence relations and amortisation tables can illustrate how and why these balances change. Once pure compound growth or decay is identified, the compound interest formula may then be used. You could also use a financial solver app on the calculator here as well.
A more complex problem can include a regular payment or withdrawal, as well as compounding growth. For such problems, the compound interest formula is not appropriate and the financial solver app should be used.

[Ashjames]

Hello everyone

I was just wondering, does any one have to answers to the NELSON further math Book (chapter on matrices?)

Please, it would really help me because I would like to know if I got them right