Bored of Studies Trial Discussion Thread. (2 Viewers)

Carrotsticks

Retired
Joined
Jun 29, 2009
Messages
9,494
Gender
Undisclosed
HSC
N/A
As a year 11 who had no knowledge of projectile motion, binomial theorem, perms & combs etc, I died several times over in the test haha.

It was an interesting experience to say the least

I'm so happy that I could angle chase the circle geo question though

TAKE THAT CARROT! :p

hehe
 

deswa1

Well-Known Member
Joined
Jul 12, 2011
Messages
2,256
Gender
Male
HSC
2012
Ah that is genius heh. Well this method will probably help me with alot of perms questions. Thanks (and props to carrot of course)
Yeah its a very nice method. And yes- thank Carrotball not me.

@Twink- I angle chased it too. I always angle chase stuff lol
 

RealiseNothing

what is that?It is Cowpea
Joined
Jul 10, 2011
Messages
4,591
Location
Sydney
Gender
Male
HSC
2013
I derped on 3 questions so far argh.

Stuffed up two limits because I used the wrong limits for my integral (terrible), and didn't realise the most obvious thing in the second part of that induction question.

Although really looking forward to Wednesday.
 
Joined
Sep 20, 2010
Messages
2,225
Gender
Undisclosed
HSC
2012
Thanks for the method!! definitely sticking it in the books. Had a question - why do we need the 8C4 bit again? (lol i already asked this on another thread...still not getting it)
 

deswa1

Well-Known Member
Joined
Jul 12, 2011
Messages
2,256
Gender
Male
HSC
2012
Thanks for the method!! definitely sticking it in the books. Had a question - why do we need the 8C4 bit again? (lol i already asked this on another thread...still not getting it)
Ok, there are 8 spaces between the 'barriers' and in these we need to place 4 vowels. So choose four spots out of eight in 8C4 ways and shove the vowels in there.

And are you coming on Wed?
 
Joined
Sep 20, 2010
Messages
2,225
Gender
Undisclosed
HSC
2012
Ohhh ic...I was thinking...choose 4 vowels out of 8 letters and was like wtf.. but you're actually choosing the spots where they go - great! I kept getting in a twist because I drew out all 11 spots and didn't know how to deal with cases where you can have two letters between the vowels etc..

I am still tossing up - still slightly sick + very far = unsure. I really want to though!
 

Carrotsticks

Retired
Joined
Jun 29, 2009
Messages
9,494
Gender
Undisclosed
HSC
N/A
Thanks for the method!! definitely sticking it in the books. Had a question - why do we need the 8C4 bit again? (lol i already asked this on another thread...still not getting it)
We want to have no two vowels together.

So what we'll do is place them in BETWEEN the consonants, so that FORCES them to be separated (ie: no two are together).

We have 7 consonants, so I'll denote them by C's.

XCXCXCXCXCXCXCX

The X's denote possible places for vowels to be placed inside, and notice that there's 8 of them.

We have 8 spots to place them, and 4 vowels.

Hence, 8C4.
 

RealiseNothing

what is that?It is Cowpea
Joined
Jul 10, 2011
Messages
4,591
Location
Sydney
Gender
Male
HSC
2013
The way I did that probability question, it's kinda different:

You put the consonants as barriers, but instead of using 8C4, I put each vowel into a gap:

The first vowel can go in 8 places, the second vowel in 7, the third in 6, and the last vowel in 5 places. So we have 8x7x6x5.

But of the vowels, there are three O's, so I divided by 3! to get rid of the arrangements repeated:



Then we arrange the consonants, which can be done in 7! ways, but divide by 2! since there are 2 H's:



Which gives you the same answer.
 
Last edited:

Carrotsticks

Retired
Joined
Jun 29, 2009
Messages
9,494
Gender
Undisclosed
HSC
N/A
The way I did that probability question, it's kinda different:

You put the consonants as barriers, but instead of using 8C4, I put each vowel into a gap:

The first vowel can go in 8 places, the second vowel in 7, the third in 6, and the last vowel in 5 places. So we have 8x7x6x5.

But of the vowels, there are three O's, so I divided by 3! to get rid of the arrangements repeated:



Then we arrange the consonants, which can be done in 7! ways, but divide by 2! since there are 2 H's:



Which gives you the same answer.
8x7x6x5 is exactly the same thing as 8P4.
 

lolcakes52

Member
Joined
Oct 31, 2011
Messages
286
Gender
Undisclosed
HSC
2012
Good paper, I got stuck once or twice and only did a quick run through. Definitely the hardest 3 unit one I've seen, more like a pure harder 3 unit paper, a 4 unit kids worst nightmare.
 

Carrotsticks

Retired
Joined
Jun 29, 2009
Messages
9,494
Gender
Undisclosed
HSC
N/A
Marking my first paper ATM, not bad. But oh my lord how I loathe tiny handwriting.
 

deswa1

Well-Known Member
Joined
Jul 12, 2011
Messages
2,256
Gender
Male
HSC
2012
Marking my first paper ATM, not bad. But oh my lord how I loathe tiny handwriting.
Oh who is it?

And you are going to kill me when you see my paper. The writing is crap and there's heaps of crossing out mixed with non crossed out stuff and all that. Hopefully you can still follow it lol- need to work on some of that setting out- especially when I've crossed out stuff and there's no room to add it (didn't want to get a new booklet though I probs should have)
 
Joined
Sep 20, 2010
Messages
2,225
Gender
Undisclosed
HSC
2012
Don't even bother with mine...lol it's worthless
 

Users Who Are Viewing This Thread (Users: 0, Guests: 2)

Top