Maths Methods 3/4 Help Thread 2011

[nacho]

Multiply the function by x then do the integral from 0 to 3 to find the mean, then find the probabilty greater than that.

Isn't this a discrete distribution since X can only take 0,1,2,3?
And are you sure the equation is right? I'm getting negative probabilities here...

yes thats the right equation, perhaps ive set it out ambiguously
it is multiplied by negative 1/30

[b^3]

Multiply the function by x then do the integral from 0 to 3 to find the mean, then find the probabilty greater than that.

Isn't this a discrete distribution since X can only take 0,1,2,3?
And are you sure the equation is right? I'm getting negative probabilities here...

yes thats the right equation, perhaps ive set it out ambiguously
it is multiplied by negative 1/30

Ok that makes sense, thats what I was trying next.
To find the mean, not median, you need to do the E(X) =x*f(x) for the values of x (add up the results of x*f(x)) and find the mean.
So 0f(0)+1f(1)+2f(2)+3f(3)=1.66
So when it exceeds it's mean is when X>1.66 i.e. x>=2
which is 17/30 (f(2)+f(3))

[Greatness]

Multiply the function by x then do the integral from 0 to 3 to find the mean, then find the probabilty greater than that.

Isn't this a discrete distribution since X can only take 0,1,2,3?
And are you sure the equation is right? I'm getting negative probabilities here...

Yeah tahts what i was looking for! haha damn gonna kill me in the exam if it doesnt specifically say, this is a pdf or binomial etc xD

[b^3]

The only reason I know this is because I did further last year and they murder you if you don't know what type of data you are looking at.
They way I remember it is:
Single values: discrete - probability table
"<" and ">" or area under it: continuous - graph with area under it - pdf
Given a p for success/fail: binomial - no graph.

[BlueSky_3]

Does anyone know what the mark allocations for our outcomes for methods throughout the year are? My teacher gave me a copy a long while ago and now I don't know where it is.

[duquesne9995]

SAC 1 10%
SAC 2 10%
SAC 3 40%
SAC 4 20%
SAC 5 20%

[adRo93]

Hello, just hoping for a hand with this question.


I keep getting A, and i don't believe the worked solution is correct. I may be doing something wrong in my CAS....



Im getting the area of  |6x-11| to be 0.611, and the area of |x| to be 1.1875, which makes sense to me because I would think that the area of |x| would be larger... And the worked solution has the right values, they just seem to be jumbled. So am I doing something wrong?

[homosapiens]

Could someone please explain how to solve questions 20 and 22 from the VCAA 2010 MM Exam 2 Multiple Choice?

[xZero]

upload the question for us?

[homosapiens]

Oops my bad! Not sure how to insert images into the post so it's attached instead

[xZero]

20. split the integral up into

we know that where F'(x)=f(x), if i integrate the first part of the integral, i have to use chain rule so it becomes , agreed? Now sub in the terminals and you'll get and since , the first part of the integral will become 10a.

The second part of the integral should be easy, you'll get 30a as the solution, now add them up and you will get 40a.

22. Don't have a specific way of doing these, just sub in all the options and see which 1 works

[homosapiens]

Thanks heaps xZero!

[pi]

Is legit notation for a condition?

[luken93]

Is legit notation for a condition?

Perhaps 1 + 2n, n c R ? haha just a suggestion

[paulsterio]

Is legit notation for a condition?

Perhaps 1 + 2n, n c R ? haha just a suggestion

Don't you mean n c Z?