Bazza's 3/4 Question Thread

[Jenny_2108]

Like where does that extra 2 come from? Adding 2pi takes to the next period, not the one indicated on the graph!?

If you look at the graph carefully, you will see m>2pi actually
As I explained before

1c) the distance of x-intercepts between 2 gradients are: 2pi+ sqr3-pi/3 + sq3-pi/3

so m=2pi+2 (sqr3-pi/3)

[Phy124]

Thanks for the help, though for 1, that's the way i did it ( vcaa method 2) but i don't see the logic behind method 1 D:



Like where does that extra 2 come from? Adding 2pi takes to the next period, not the one indicated on the graph!?

The key factor is that the distance between the x-intercept of tangent A and , is the same as the distance between tangent B and

You know that the x-intercept of tangent A is so the distance between this point and is

So the distance from to is

Then the distance from to is

Then the distance from to the x-intercept of tangent B is an extra along the x-axis.

Meaning the total distance between the two x-intercepts of tangent A and tangent B is equal to;



Pretty sure that's what you're asking?

[WhoTookMyUsername]

Thanks rangaa, im still unsure about this part though "

The key factor is that the distance between the x-intercept of tangent A and , is the same as the distance between tangent B and

As in, what feature of a trig graph brings about this relationship? I know from the graph picture it looks quite obvious, but how do you know the distance between 0 and xint (a) is = distance between 2pi and x int ( b )?
Is it because the tangent at B will be equal to the tangent at 7pi/3 ? ( a (x) + 2pi)? How do  you know this?

I think i must be missing something simple D:

2) random variable x has a normal distribution and its mean is u. Given pr (5<x<u)=0.37, then pr(x>2u-5) equals?

Thanks

[WhoTookMyUsername]

In addition to ^ (if anyone can answer it xD)

if you have a normal distribution, let's say X, what is the normal distribution of 2X? (graphically/what does mean U and standard dev o become?)

I was thinking that VAR(2X) = 4Var(X) therfore SD(2X) = 2SD(X)
Is this correct?


Thanks!

[brightsky]

yes.

[Jenny_2108]

In addition to ^ (if anyone can answer it xD)

if you have a normal distribution, let's say X, what is the normal distribution of 2X? (graphically/what does mean U and standard dev o become?)

I was thinking that VAR(2X) = 4Var(X) therfore SD(2X) = 2SD(X)
Is this correct?


Thanks!

Mean doesnt change

[brightsky]

In addition to ^ (if anyone can answer it xD)

if you have a normal distribution, let's say X, what is the normal distribution of 2X? (graphically/what does mean U and standard dev o become?)

I was thinking that VAR(2X) = 4Var(X) therfore SD(2X) = 2SD(X)
Is this correct?


Thanks!

Mean doesnt change

it should. the mean of the image should be double the original.

[Jenny_2108]

In addition to ^ (if anyone can answer it xD)

if you have a normal distribution, let's say X, what is the normal distribution of 2X? (graphically/what does mean U and standard dev o become?)

I was thinking that VAR(2X) = 4Var(X) therfore SD(2X) = 2SD(X)
Is this correct?


Thanks!

Mean doesnt change

it should. the mean of the image should be double the original.

You are right
E(2X)=2E(X)

I know, I'm so bad at probability 

[TrueTears]

In addition to ^ (if anyone can answer it xD)

if you have a normal distribution, let's say X, what is the normal distribution of 2X? (graphically/what does mean U and standard dev o become?)

I was thinking that VAR(2X) = 4Var(X) therfore SD(2X) = 2SD(X)
Is this correct?


Thanks!

Normality preserves linear transformations. That is, a normal random variable is closed under linear transforms. http://en.wikipedia.org/wiki/Normal_distribution#Miscellaneous

If

[WhoTookMyUsername]

thanks
For maths is it generally 1 mark = 1 study score lost ?
Do you need full marks in both exams to get 50?

[charmanderp]

thanks
For maths is it generally 1 mark = 1 study score lost ?
Do you need full marks in both exams to get 50?

From what I know if you have full SAC marks, a 40 and 79 will get you a 50, and a 40 and 80 will get you Premier's.

You'd possibly lose 1 study score integer for each mark lost on Exam 2, probably not the case for Exam 1 due to the weighting. And it'd depend on your SACs too.

[Jenny_2108]

^ If you don't get full marks in every single SAC, is it possible to get 50?

[charmanderp]

Yes,

[BubbleWrapMan]

I didn't get full marks on any SAC last year, haha

[Jenny_2108]

I didn't get full marks on any SAC last year, haha

Stop that! You ranked 2 and got 100% in both exams!
At my school, the SACs are not extremely hard so getting full maks is still top 3-5