VCE Methods Question Thread!

[cosine]

Thankyou so much  but i cant see what you have done.

Because we have three squared, and also the whole brackets are squared, you can bring the whole thing to the power of 2 and expand the brackets

[timton]

Hi everyone

Just wondering if there is a correct notation we should be using for Inverse Normal, as we cannot use invNorm as it is calculator notation. I know that normal distribution is N~(mean, var) but what is it for inverse?

Thanks everyone

[knightrider]

(Image removed from quote.)

Because we have three squared, and also the whole brackets are squared, you can bring the whole thing to the power of 2 and expand the brackets

Thanks cosine 

[Floatzel98]

Hey guys. I have only just finished the first part of probability (Discrete Random Variables) and my teacher has told me that our class will be going onto Markov Chains next, but we will only have to do the first 2 subchapters within it (I'm using the Essentials Textbook) since it isn't a major part of the course? Do I just go ahead and do what she says or just do everything anyway?

These are the chapters from the textbook if it helps:
16.1 - Using Matrices to represent conditional probability
16.2 - Markov Chains
16.3 - Steady State of a Markov Chain
16.4 - Comparing Run Length for Bernoulli Sequences and Markov Chains

Another thing  . This means that she is making up skip over Binomial Distributions for a while, which is chapter 15. Does it make a difference if I do 16 before 15? Or do i just disregard my teacher completely?

Thanks

[keltingmeith]

I'm just going to be a dick and reserve the right to be quick and blunt with answers.
Not trying to be rude, I swear, but I've had little sleep and may be a little irritable.

Hi everyone

Just wondering if there is a correct notation we should be using for Inverse Normal, as we cannot use invNorm as it is calculator notation. I know that normal distribution is N~(mean, var) but what is it for inverse?

Thanks everyone

Nah, there's nothing. Technically, we only have an inverse normal for the standard normal, so there is really no need for notation (also the fact that the inverse normal is not a distribution, and the notation you've used indicates that N has a distribution)

To memory, there's something in the resources topic that explains how to avoid CAS notation specifically for this. Have you given that a look see?

Hey guys. I have only just finished the first part of probability (Discrete Random Variables) and my teacher has told me that our class will be going onto Markov Chains next, but we will only have to do the first 2 subchapters within it (I'm using the Essentials Textbook) since it isn't a major part of the course?

lolwut.

Do I just go ahead and do what she says or just do everything anyway?

These are the chapters from the textbook if it helps:
16.1 - Using Matrices to represent conditional probability
16.2 - Markov Chains
16.3 - Steady State of a Markov Chain
16.4 - Comparing Run Length for Bernoulli Sequences and Markov Chains

I'd at least be reading 16.3
16.4 you could probably skip rather readily, but you won't even think about steady state unless you see it, and that's arguably the most important part of Markov Chains in general (not just VCE)

Another thing  . This means that she is making up skip over Binomial Distributions for a while, which is chapter 15. Does it make a difference if I do 16 before 15? Or do i just disregard my teacher completely?

Nah, that part is legitimately okay. Don't need Binomial for Markov - one assumes independence, the other assumes otherwise. Two different things.

[knightrider]

How would you do this question relating to the image attached?

Show that the turning point on the x-axis is

[keltingmeith]

How would you do this question relating to the image attached?

Show that the turning point on the x-axis is (Image removed from quote.)

I'd start by differentiating, and then considering what happens to the gradient at a turning point.

[cosine]

In general, on the exam, if the question says express to one decimal point and you do it to two, and the question is one mark, im guessing no mark is allocated? And what if the second scenario, but it is two marks?

[keltingmeith]

In general, on the exam, if the question says express to one decimal point and you do it to two, and the question is one mark, im guessing no mark is allocated? And what if the second scenario, but it is two marks?

If you report the answer to the wrong amount of decimal places, your answer is considered as wrong, and you will lose any/all answer marks (which is generally just one mark).

[knightrider]

I'd start by differentiating, and then considering what happens to the gradient at a turning point.

still dont know what to do ? Could you please explain?

there is no c when you diff it

[cosine]

If a question says the intercept of f(x) is given in the form of log(m), find m, and the answer happens to be log(2), and the question is 1 mark. You would not get the mark if you just found the intercept as log(2) and without stating m=2, right?

[e^1]

How would you do this question relating to the image attached?

Show that the turning point on the x-axis is (Image removed from quote.)

Here are some hints, and a partial solution which leads to the answer. Please attempt this question yourself (without looking at solution), and don't try to randomly look at hints unless you need them. The first hint is free though.

Hint 1

We want to find the value of x from the point such that:

• , which represents the point is a stationary point.
• , indicating that the point is on the x-axis (ie. y = 0).

Thus we have the simultaneous equations:



Now we want to find the value of x such that these two equations are satisfied. We know that the point has y-value of 0. So our point, so far, is .

Hint 2

Hint 3

Now you may have two equations, the left hand side of both of those equations being polynomials of degree two.

You could solve both of them using the quadratic formula on both equations, and find the value x such that both equations are satisfied. But this could get ugly.

On the other hand, like in hint 2, we removed the damned term. What about this time, we remove the term?

Think about it.

End solution

The two equations, when using hints 1 and 2, are:



Following from hint 3, we could multiply the second equation by so  that we can remove altogether:



Hence:


Resulting in the desired answer:


So the desired turning point is therefore with .

[IndefatigableLover]

If a question says the intercept of f(x) is given in the form of log(m), find m, and the answer happens to be log(2), and the question is 1 mark. You would not get the mark if you just found the intercept as log(2) and without stating m=2, right?

Yes that is true.

[qwerty101]

question4 and question 10c,d pls

[Floatzel98]

question4 and question 10c,d pls

For question 10, Zealous already answered this question in detail a few pages back. Try to find that, it should help.

For question 4 try constructing a tree diagram starting from the probability of selecting each coin. Then find the sample space of getting a heads and tails from coin A (HT, TH), find that probaility and then divide that by the total probability of getting a heads and tails from both coins. It should work