VCE Methods Question Thread!

[dinosaur93]

cheers

[hongs-]

Can someone please help me with this question, I chose A but got it wrong. I don't know how to figure it out
its vcaa 2008 qn

Let X be a discrete random variable with a binomial distribution. The mean of X is 1.2 and the variance of X is 0.72.
The values of n (no. of independent trials) and p ( probability of success in each trial) are

A n=4 p=0.3
B n=3 p=0.6
C n=2  p=0.6
D n=2  p=0.4
E  n=3  p=0.4

[aishuwa1995]

E(x)=np
np=1.2

Var(x)=np(1-p)
0.72=np(1-p)

Solve using calculator to get n=3 and p=0.4 (E)

[hongs-]

thankyou!!!

[Tonychet2]

kilbaha 2010 question 12 MC

the average rate of the change of the function with the rule y = 2cos(2x) over 0 < x < pi/8 is equal to...
? hoow do you do this?

i used the formula and the answer wasnt 4sqrt(2)/ pi

[BubbleWrapMan]

Which formula did you use? It should be the net change in y divided by the net change in x.

[FlorianK]

kilbaha 2010 question 12 MC

the average rate of the change of the function with the rule y = 2cos(2x) over 0 < x < pi/8 is equal to...
? hoow do you do this?

i used the formula and the answer wasnt 4sqrt(2)/ pi

let f(x)=2cos(2x)
f(pi/8)=sqrt(2)
f(0)=2
(sqrt(2)-2)/(pi/8)=(8/pi)*(sqrt(2)-2)

Don't know what kind of mistake you made

[Tonychet2]

OHHHH woops im a complete idiot, just realised it wasnt asking for the average value but it was the average rate of change .. my bad - read theq uestion as the average value of the function instead of the average rate of change

[Hutchoo]

OHHHH woops im a complete idiot, just realised it wasnt asking for the average value but it was the average rate of change .. my bad - read theq uestion as the average value of the function instead of the average rate of change

Mate, I made the EXACT same mistake!

[hongs-]

Has anyone done the 2008 VCAA extended question 2d ?

http://www.vcaa.vic.edu.au/Documents/exams/mathematics/2008mmcas2-w.pdf

[Phy124]

Has anyone done the 2008 VCAA extended question 2d ?

http://www.vcaa.vic.edu.au/Documents/exams/mathematics/2008mmcas2-w.pdf

You want to solve the two integrals simultaneously.

I'm not sure what calculator you use, but with the TI89 the syntax was something like:

[Homer]

Bit too long if done by hand ;/

[hongs-]

Has anyone done the 2008 VCAA extended question 2d ?

http://www.vcaa.vic.edu.au/Documents/exams/mathematics/2008mmcas2-w.pdf

You want to solve the two integrals simultaneously.

I'm not sure what calculator you use, but with the TI89 the syntax was something like:

Ohh I use the Ti-nspire CAS, but yeah I got the answer ,thanks

Yeah true.  The by hand way, is a bit confusing, I'll just stick to CAS

[hongs-]

2008 exam 2 question 4b??

Is there a way to find the answer to question 4b on CAS?
I'm trying to solve it on cas and i get the general solution but i dont know what to do next

[polar]

you have to put the restrictions to get the solutions

if he has toast twice between monday and wednesday, but had toast on monday, the combinations are TTB or TBT