QCE GENERAL MATHS Q&A THREAD
What is this thread for?
If you have general questions about the QCE General Maths course (both Units 1&2 and 3&4) or how to improve in certain areas, this is the place to ask! 👌
Who can/will answer questions?
Everyone is welcome to contribute; even if you're unsure of yourself, providing different perspectives is incredibly valuable.
Please don't be dissuaded by the fact that you haven't finished Year 12, or didn't score as highly as others, or your advice contradicts something else you've seen on this thread, or whatever; none of this disqualifies you from helping others. And if you're worried you do have some sort of misconception, put it out there and someone else can clarify and modify your understanding!
There'll be a whole bunch of other high-scoring students with their own wealths of wisdom to share with you, so you may even get multiple answers from different people offering their insights - very cool.
To ask a question or make a post, you will first need an ATAR Notes account. You probably already have one, but if you don't, it takes about four seconds to sign up - and completely free!
What have you been taught? I'm a bit more curious as to what your thought processes are with these questions.
For the first one: there's a lot of irrelevant information you can ignore (consider why this is the case)
For the second one: a bit of a tougher question, so I want to see what you've tried first. Check also for typos in the question, something seems a bit off to me (unless it's just me not being able to read).
So when it comes to reducing balance loans, I have been taught there are 4 ways to solve them. First, is by using a payment schedule where you go through each repayment period and calculate the interest rate, the interest paid, the withdrawal amount, and the principle reduction (or increase if it is an investment). The second way I have been taught is to use recurrence relations, which is:
A0 = the principle, An+1 = r x An - R
With r being 1 + the interest rate (in decimal form), R = repayment amount
The third method I have been taught is to use the annuities formula. In this case, I used the one with -n in it.
The final method I have been told is to use a formula that combines the compound interest formula with the annuities formula, which looks like this:
A = P(1+i)n-M([(1+i)n-1] divided by i)
So, for Question 11, I initially was trying to find A (in both the annuities and the formula above) but this wasn't going anywhere. So, I randomly tried 2215.42 \times 100 (because of the compounding periods) - 120000 and this gave me the answer. But, I don't know why because I have been taught to find the total interest you need to do this formula:
A + n x R - P
I did try this formula but I kept getting weird A values (like a negative or a value in the millions).
But, for question 12, I tried both the mixed compound interest and annuities formula and just the annuities formula by itself and I got like $-536.604 (with the mixed formula) and $89042.82 (with the annuities formula). I even tried just doing the recurrence relations method but the principle was just decreasing too fast for it to be even close to $2136.07 (I got -1068.49 somehow).
The main thing that trips me up, other than the formula issue, is I don't know what to do to the interest rate when it says adjusted half-yearly. If it said compounding half-yearly, I'll immediately divide the interest rate by 200 (as this transforms the nominal rate to the compounding rate). I did this with both the questions, but it didn't work, which led me to believe that you do something different to the interest when it says adjusted.
Up until this Jacaranda worksheet, I was completely confident with reducing balance loans and annuities. But them labeling questions like these as simple familiar is making me worried as I don't feel as though I have covered these types of questions. The questions I normally get are something like the one attached.
Hopefully I am making sense,
Luke