VCE Methods Question Thread!

[FlorianK]

You won't need to use it unless it's on your formula sheet.

But do we need it for like Kilbaha and stuff?

[pi]

You won't need to use it unless it's on your formula sheet.

But do we need it for like Kilbaha and stuff?

I don't remember seeing it.

[bonappler]

Find the relationship between m and k such that the line with equation y=mx intersects the curve with equation y=x^2(x-k) at the point (0,0) and one other point only.
I have found the intercepts of the curve x^3-kx^2-mx but where do I go from there? Do I just say k^2+4m>0

[Lasercookie]

Find the relationship between m and k such that the line with equation y=mx intersects the curve with equation y=x^2(x-k) at the point (0,0) and one other point only.

(so here's our point (0,0) intersection)


We need to find values where they'll only be one x-intercept. This is when the quadratic discriminant is equal to zero (looking at the quadratic formula might be a formulaic way of seeing this will be true).



The question only wanted the relationship between k and m, so:

[bonappler]

Oh okay that makes sense, I forgot about the two intercepts. Thanks.

[monkeywantsabanana]

Hey guys,
Can someone please explain this stuff please? This is regards to probability

X~(x,y)
N~(x,y)

What does it actually mean? Also, are there any other ones that I should be aware of? I did MAV yesterday and came across this.... and didn't understand what the numbers inside the brackets meant.

Thanks heaps.

[Lasercookie]

X~(x,y)
N~(x,y)

That notation is how you write it without using calculator syntax. It'll crop up like that in questions too. But what you've written there, that's incomplete isn't it? It should say what kind of distribution it is.

X, N = the random variable
~ = distributed
(x,y) will depend on how it's being distributed.

Normally it'd say if it's Bi(x,y) - sometimes B(x,y) - in which case the convention is Bi(number of trials, probability of success) or
N(x,y) where it's a normal distribution N(mean, variance)

X is distributed binomially, with n trials and p probability of success

Z is distributed normally, with a mean of and a variance of (note that it's not given as the standard deviation)

There's a pretty good guide here: Re: Mathematical Methods CAS Resources

[generalkorn12]

For MAV 2011 Exam, I'm having trouble with 3c, the ans seems to divide probabilities or something...

Thanks.   

[Jenny_2108]

For MAV 2011 Exam, I'm having trouble with 3c, the ans seems to divide probabilities or something...

Thanks.   

They divide because its probability of overweight (X>1010) given probability of rejected (X>1010) and (X<992)

[someone.called]

hey I need some help with these trig questions, I'm struggling with these, please show working?

solve for eq for x, where 0 is less than or equal to x, and 2pi is greater than or equal to x

sin(2x+pi/3)=0.5

cos(x+pi/4)=squareroot-3/2

tan(2x)=1

[Homer]

hey I need some help with these trig questions, I'm struggling with these, please show working?

solve for eq for x, where 0 is less than or equal to x, and 2pi is greater than or equal to x

sin(2x+pi/3)=0.5

cos(x+pi/4)=squareroot-3/2

tan(2x)=1

is that right?

[Phy124]

is that right?

That it is.

[barydos]

For a standard normal distribution, Pr(Z< c) =a, 0<c<3 and 0<a<1.
Find Pr(|z| < c).

I got the answer a weird way, but I'm sure there's a better proper method of doing it...

[FlorianK]

For a standard normal distribution, Pr(Z< c) =a, 0<c<3 and 0<a<1.
Find Pr(|z| < c).

I got the answer a weird way, but I'm sure there's a better proper method of doing it...

What is the answer?
is it a/2?

[barydos]

The answer is 2a-1
Supposedly Pr(|Z|< c) = Pr(-c<Z<c)
and then you work out 2a-1
but i'm trying to get my head around Pr(|Z| < c) = Pr(-c<Z<c)