• Want to help us with this year's BoS Trials?
    Let us know before 30 June. See this thread for details
  • Looking for HSC notes and resources?
    Check out our Notes & Resources page

2017 HSC Mathematics Extension 2 paper thoughts? (1 Viewer)

shervos

Member
Joined
Jul 17, 2015
Messages
39
Gender
Male
HSC
2015
can someone explain the last question plz
i got 486
You probably got 486 by plugging values into the expression in the 2nd last part. However this gives the total number of ways under the assumption that not all colours have to be used.
To remove these cases, firstly note that it is impossible to use one colour to colour the grid, so we consider the cases with 2 colours. From 3 coliurs, we can choose 2 colours in 3c2 ways, and for each combination of 2 colours, there are two ways they can be used to colour the grid. So our final answer is 486-3c2*2 =480 as stated above
 

mkwon99

New Member
Joined
Oct 18, 2016
Messages
15
Gender
Undisclosed
HSC
N/A
So let the three 3 colours be R, B and G,
R B R B
B R B R
and so on, while the R and B can switch spots => 2 ways
Since 3 colours must be painted at least once, we must find more cases like above
since this applies to any 2 colours, there are 3C2 ways to choose the colours
hence: total ways = 486 - 3C2 * 2
 

pikachu975

Premium Member
Joined
May 31, 2015
Messages
2,739
Location
NSW
Gender
Male
HSC
2017
Rip arg(z/w) I did pi - tan^-1 (z/w) for some reason I turned retarded. Would I get 1/2
 

shervos

Member
Joined
Jul 17, 2015
Messages
39
Gender
Male
HSC
2015
Paper looked alright to me. Pretty uninspiring Q16 as per usual from the past few years
Yeah so it seems to be the case that while top students would've absolutely loved this exam cause free marks (or hated it because it was too easy and boring), students at the e3/borderline e4 level struggled with the paper.
This really reminds me of the case with the 2013 HSC paper
 

Owlu

New Member
Joined
May 15, 2017
Messages
1
Gender
Undisclosed
HSC
N/A
I thought they didn't give half marks
 

GiraCubed

New Member
Joined
Oct 21, 2016
Messages
6
Gender
Male
HSC
2017
I felt Questions 11-14 were great, and then 15-16 were the worse thing I've ever encountered. I choked some stuff in 15 but I basically felt I was doing an exam out of 85 after seeing 16.

I'm also sad that there wasn't more/tougher Mechanics questions in question 15/16. Really thought there'd be a Banked Track Q. Either way I'm trying not to think about the negatives lmao
 

pikachu975

Premium Member
Joined
May 31, 2015
Messages
2,739
Location
NSW
Gender
Male
HSC
2017
Lol they ripped off integral of x tan^-1 x from trial papers
 

same1111

Member
Joined
Feb 16, 2017
Messages
46
Gender
Undisclosed
HSC
N/A
screw q16 why the hell would do they do another probabilty question again when they did it last year. The first part of it was alright tho.. I didnt get the volumes question however.
 

Commando007

Member
Joined
Nov 2, 2015
Messages
57
Gender
Male
HSC
2017
You probably got 486 by plugging values into the expression in the 2nd last part. However this gives the total number of ways under the assumption that not all colours have to be used.
To remove these cases, firstly note that it is impossible to use one colour to colour the grid, so we consider the cases with 2 colours. From 3 coliurs, we can choose 2 colours in 3c2 ways, and for each combination of 2 colours, there are two ways they can be used to colour the grid. So our final answer is 486-3c2*2 =480 as stated above
So let the three 3 colours be R, B and G,
R B R B
B R B R
and so on, while the R and B can switch spots => 2 ways
Since 3 colours must be painted at least once, we must find more cases like above
since this applies to any 2 colours, there are 3C2 ways to choose the colours
hence: total ways = 486 - 3C2 * 2


thanks guys
 

pikachu975

Premium Member
Joined
May 31, 2015
Messages
2,739
Location
NSW
Gender
Male
HSC
2017
RIP 9/10 in MC I didn't see the |z-1| for q3 I just did z so I typed in my calculator wrong
 

shervos

Member
Joined
Jul 17, 2015
Messages
39
Gender
Male
HSC
2015
but we haven't ;)

they need to step up their game, or hire us to write questions.
Yeah the bos trials are great actually.
Am disappointed that you let someone get over 70% though.


Naw I am just kidding, well done to both your team and that individual
 

calamebe

Active Member
Joined
Mar 19, 2015
Messages
462
Gender
Male
HSC
2017
Yeah the bos trials are great actually.
Am disappointed that you let someone get over 70% though.


Naw I am just kidding, well done to both your team and that individual
If you want, you can discount me as I did 4U last year, so then no one sitting the HSC this year got over 70%
 

shervos

Member
Joined
Jul 17, 2015
Messages
39
Gender
Male
HSC
2015
If you want, you can discount me as I did 4U last year, so then no one sitting the HSC this year got over 70%
Oh wow, I guess I'll retract my previous statement then.
Good on you either way - do you plan on pursuing mathematics in university?
 

Users Who Are Viewing This Thread (Users: 0, Guests: 1)

Top